bluuebunny/crossref_metadata_2025 huggingface dataset:
Research on dynamic characteristics and control strategy of energy release process of liquid air energy storage system
Authors: Na Rigele , Meng Keqilao , Liu Qing , Hai Rihan , Zhang Zhanqiang
Published: April 2024

The liquid air energy storage (LAES) technology has received widespread attention for its advantages of high energy storage density, a wide range of applications, safety, environmental protection and hygiene, flexible device regulation, and large energy storage scale and is developing toward high-parameter and large-capacity energy storage. However, due to the late start of research in China, large-scale LAES has not been put into commercial operation so far, and the lack of in-depth understanding of the dynamic characteristics of LAES has seriously impeded the development of the system design and regulation technology, which limits the development and popularization of LAES. In this study, a dynamic mathematical model of the liquid air energy storage system is established based on the SIMULINK platform of MATLAB software. The dynamic characteristics of the system in the energy release stage are analyzed, a control model of the grid-connected speed control system is established, and an optimized control strategy is obtained by using a linear active disturbance rejection controller and by analyzing the response under typical disturbances. The model and the results of this study provide a reference for the understanding of the dynamic characteristics of LAES and the control of the speed control system, and the control strategy can effectively reduce the problem of high overshooting of the rotor of the expander and reach a stable state in a shorter time, which is of practical significance for promoting the application and popularization of LAES.
Comparison of Mg-based liquid metal ion sources for scalable focused-ion-implantation doping of GaN
Authors: Titze Michael , Katzenmeyer Aaron , Frisone Sam , Ohlhausen James A. , Flores Anthony , Campbell DeAnna , Li Bingjun , Wang Yongqiang , Han Jung , Bielejec Edward S. , Goldman Rachel S.
Published: April 2024

We compare the suitability of various magnesium-based liquid metal alloy ion sources (LMAISs) for scalable focused-ion-beam (FIB) implantation doping of GaN. We consider GaMg, MgSO4●7H2O, MgZn, AlMg, and AuMgSi alloys. Although issues of oxidation (GaMg), decomposition (MgSO4●7H2O), and excessive vapor pressure (MgZn and AlMg) were encountered, the AuMgSi alloy LMAIS operating in a Wien-filtered FIB column emits all Mg isotopes in singly and doubly charged ionization states. We discuss the operating conditions to achieve <20 nm spot size Mg FIB implantation and present Mg depth profile data from time-of-flight secondary ion mass spectrometry. We also provide insight into implantation damage and recovery based on cathodoluminescence spectroscopy before and after rapid thermal processing. Prospects for incorporating the Mg LMAIS into high-power electronic device fabrication are also discussed.
Ultrafast THz emission spectroscopy of spin currents in the metamagnet FeRh
Authors: Lv Yinchuan , Shim Soho , Gibbons Jonathan , Hoffmann Axel , Mason Nadya , Mahmood Fahad
Published: April 2024

Heterostructures of ferromagnetic (FM) and noble metal (NM) thin films have recently attracted considerable interest as viable platforms for the ultrafast generation, control, and transduction of light-induced spin currents. In such systems, an ultrafast laser can generate a transient spin current in the FM layer, which is then converted to a charge current at the FM/NM interface due to strong spin–orbit coupling in the NM layer. Whether such conversion can happen in a single material and how the resulting spin current can be quantified are open questions under active study. Here, we report ultrafast THz emission from spin–charge conversion in a bare FeRh thin film without any NM layer. Our results highlight that the magnetic material by itself can enable spin–charge conversion in the same order as that in a FM/NM heterostructure. We further propose a simple model to estimate the light-induced spin current in FeRh across its metamagnetic phase transition temperature. Our findings have implications for the study of the ultrafast dynamics of magnetic order in quantum materials using THz emission spectroscopy.
On thermal stability of Fröhlich polarons in bulk and nano-structured polar solids II: Diabatic ionization and depolarization
Authors: Ligatchev Valeri
Published: April 2024

In Paper I of this bipartite article, the two-particle vibrational DOS functions for spatially confined longitudinal acoustic and longitudinal optic phonons are implemented at evaluation on Fröhlich Polarons (FP) decay probability via the “Klemens channel” and lifetime for FP states confined within InAs quantum dots. Here, an alternative model based on the idea of diabatic thermally activated excitation of the FP charge carrier and consecutive lattice “depolarization” is used for evaluations on the spectral dependence of the phononic and polaronic lifetime(s). Key parameters of the “depolarization” phenomenon are evaluated quantitatively using the “entirely quantum” generalized “displaced harmonic oscillator” framework, which is closely related in spirit to the so-called “Feynman polaron” approximation.
Ge doping of α-Ga2O3 thin films via mist chemical vapor deposition and their application in Schottky barrier diodes
Authors: Wakamatsu Takeru , Isobe Yuki , Takane Hitoshi , Kaneko Kentaro , Tanaka Katsuhisa
Published: April 2024

We performed Ge doping of α-Ga2O3 thin films grown on m-plane sapphire substrates using mist chemical vapor deposition. Although the typical growth rate was high at 4 μm/h, the resultant α-Ga2O3 thin films exhibited high crystallinity. We controlled the carrier density in the range of 8.2 × 1016–1.6 × 1019 cm−3 using bis[2-carboxyethylgermanium(IV)]sesquioxide as the Ge source. The highest mobility achieved was 66 cm2 V−1 s−1 at a carrier concentration of 6.3 × 1017 cm−3. Through secondary ion mass spectrometry analysis, a linear relationship between the Ge concentration in the α-Ga2O3 thin films and the molar ratio of Ge to Ga in the source solution was established. The quasi-vertical Schottky barrier diode fabricated using the Ge-doped α-Ga2O3 thin films exhibited an on-resistance of 7.6 mΩ cm2 and a rectification ratio of 1010. These results highlight the good performance of the fabricated device and the significant potential of Ge-doped α-Ga2O3 for power-device applications.
A southern range extension for Sminthopsis macroura in Western Australia, at Eucla
Authors: Umbrello Linette S. , Beerkens Nathan , Keen Joshua , Schmidt Sylvie , Teale Roy J. , Travouillon Kenny J. , Westerman Michael , Baker Andrew M.
Published: April 2024

The stripe-faced dunnart (Sminthopsis macroura) is one of the most widespread dasyurids in Australia, occurring mostly in semiarid and arid habitats. It is not known to inhabit coastal regions of southern Australia, and no records have previously been recorded from latitudes greater than 28.5°S in Western Australia. Following the capture of an individual south of the known species range provisionally identified based on external morphology as S. macroura, we used DNA and craniodental morphology to corroborate the specimen’s identification, providing a record of the species at Eucla, Western Australia. This represents a large range extension for S. macroura of 630 km from the nearest confirmed records of the species in Western Australia and South Australia.
Prejudice towards regional accents of Philippine English
Authors: Quinto Edward Jay M. , Ong Ardvin Kester S. , Yabut Gillianne U. , Muralla Gary Abraham M. , Valenzuela Ralph Anthony J. , Villariba Ydel Dominique C.
Published: April 2024

This study examines linguistic prejudice towards the accents of three regional varieties of Philippine English: Cebuano English, Ilocano English, and Tagalog English. Data were collected using a verbal-guise technique taken by 982 listener-judges, who were selected using a purposive sampling technique. Results showed an overall more favorable attitude towards Tagalog English. Cebuano English and Ilocano English speakers were judged as less socially attractive and less competent compared to their Tagalog English counterparts. In the multilingual Philippines, where languages in the periphery, i.e. languages other than English and Tagalog, face negative stereotypes, the results indicate potential linguistic prejudice towards accents that individuals view as deviating from the standard, i.e. the Tagalog English accent as ‘the’ standard of Philippine English. The findings are discussed in light of the ongoing observation of the development of Philippine English in the Schneiderian model of postcolonial Englishes.
Bilingual children’s online processing of relative clauses
Authors: Katsika Kalliopi , Lialiou Maria , Allen Shanley E. M.
Published: April 2024

Long-distance dependencies such as relative clauses (RCs) are known to be vulnerable in heritage grammars (e.g.,
Montrul, 2008). Previous studies in RC comprehension have shown that heritage
language (HL) children show similar comprehension to monolingual children (Jia & Paradis,
2020), while differential performance has also been found (Kidd et al.,
2015). The present study investigates 11–13-year-old monolingual and German-dominant HL children’s real-time parsing
strategies in subject relative clause (SRC) and object relative clause (ORC) processing in Greek. We conducted a self-paced
listening task in Greek in which we manipulated the type of RC (subject vs. object), and the RC internal word order (canonical vs.
scrambled). Our analyses revealed no significant group differences between HL and monolingual children. Both groups of children
processed SRCs faster than ORCs on the critical RC verb segment. We also examined if case-marked pre-verbal NPs would facilitate
the processing of ORC structures. Although children processed pre-verbal faster than post-verbal NPs, ORC structures with
pre-verbal NPs received the lowest scores in the grammaticality judgment task. We discuss these findings on the grounds of
Relativized Minimality (Friedmann et al., 2009) and Fodor and Inoue’s (2000) Diagnosis and Repair Model.
Spatial covariation between infection levels and intermediate host densities in two trematode species
Authors: Hansen E.K. , Poulin R.
Published: April 2024

Both theoretical arguments and empirical evidence suggest that parasite transmission depends on host density. In helminths with complex life cycles, however, it is not clear which host, if any, is the most important. Here, the relationships between the abundance of metacercariae in second intermediate hosts, and the local density of both the first and second intermediate hosts of two trematode species, are investigated. Samples of the snail Potamopyrgus antipodarum, the amphipod Paracalliope fluviatilis and the isopod Austridotea annectens were collected from ten stations in a New Zealand lake. In the trematode Coitocaecum parvum, neither the density of the snail first intermediate host nor that of the amphipod second intermediate host correlated with infection levels in amphipods. In contrast, in the trematode Microphallus, infection levels in isopod second intermediate hosts were positively associated with isopod density and negatively associated with the density of snail first intermediate hosts. These relationships are explained by a negative correlation between snail and isopod densities, mediated in part by their different use of macrophyte beds in the lake. Overall, the results suggest that, at least for Microphallus, local infection levels depend on local intermediate host densities.
NCRP commentary no. 33—recommendations for stratification of equipment use and radiation safety training for fluoroscopy
Authors: Miller Donald L , Balter Stephen
Published: April 2024

National Council on Radiation Protection and Measurements Commentary No. 33 ‘Recommendations for Stratification of Equipment Use and Radiation Safety Training for Fluoroscopy’ defines an evidence-based, radiation risk classification for fluoroscopically guided procedures (FGPs), provides radiation-related recommendations for the types of fluoroscopes suitable for each class of procedure, and indicates the extent and content of training that ought to be provided to different categories of facility staff who might enter a room where fluoroscopy is or may be performed. For FGP, radiation risk is defined by the type and likelihood of radiation hazards that could be incurred by a patient undergoing a FGP. The Commentary also defines six training groups of facility staff based on their role in the fluoroscopy room. The training groups are based on a combination of job descriptions and the procedures in which these individuals might be involved. The Commentary recommends the extent and content of training that should be provided to each of these training groups. It also provides recommendations on training formats, training frequency, and methods for demonstrating that the learner has acquired the necessary knowledge.
Comparison of lifetime mortality risk, incidence risk, and DALYs of baseline cancer rates among countries as a benchmark for radiation-related cancer risk
Authors: Hirouchi Jun , Kujiraoka Ikuo , Takahara Shogo , Takada Momo , Schneider Thierry , Kai Michiaki
Published: April 2024

Statistical benchmark data are necessary when considering the basis for radiation protection criteria based on calculated risks. We herein focused on baseline mortality and incidence cancer rates as benchmark data collected from 33 countries. Furthermore, we calculated the lifetime mortality and incidence risks and disability-adjusted life years (DALYs) for all solid cancers, colon cancer, lung cancer, breast cancer, thyroid cancer, and leukemia using the baseline cancer rates and compared them among the countries. The results showed that the lifetime mortality and incidence risks and DALYs for all solid cancers differed among the countries by a factor of 2–4 for males and 2–3 for females; these were low in less-developed countries. Our study proposed that health risk based on baseline cancer rates should be the benchmark for comparing radiation cancer risks.
Localized surface plasmon resonance and atomic force microscopy study of model lipid membranes and their interactions with amyloid and melatonin
Authors: Mei Nanqin , Liang Jingwen , McRae Danielle M , Leonenko Zoya
Published: April 2024

Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterized by the accumulation of amyloid plaques in the brain. The toxicity of amyloid to neuronal cell surfaces arises from interactions between small intermediate aggregates, namely amyloid oligomers, and the cell membrane. The nature of these interactions changes with age and disease progression. In our previous work, we demonstrated that both membrane composition and nanoscale structure play crucial roles in amyloid toxicity, and that membrane models mimicking healthy neuron were less affected by amyloid than model membranes mimicking AD neuronal membranes. This understanding introduces the possibility of modifying membrane properties with membrane-active molecules, such as melatonin, to protect them from amyloid-induced damage. In this study, we employed atomic force microscopy and localized surface plasmon resonance to investigate the protective effects of melatonin. We utilized synthetic lipid membranes that mimic the neuronal cellular membrane at various stages of AD and explored their interactions with amyloid-β (1–42) in the presence of melatonin. Our findings reveal that the early diseased membrane model is particularly vulnerable to amyloid binding and subsequent damage. However, melatonin exerts its most potent protective effect on this early-stage membrane. These results suggest that melatonin could act at the membrane level to alleviate amyloid toxicity, offering the most protection during the initial stages of AD.
Synthesis of novel coumarin-triazole hybrids and first evaluation of the 4-phenyl substituted hybrid loaded PLGA nanoparticles delivery system to the anticancer activity
Authors: Arvas Busra , Ucar Burcu , Acar Tayfun , Varli Hanife Sevgi , Arvas Melih Besir , Aydogan Feray , Yolacan Cigdem
Published: April 2024

Despite the discovery of many chemotherapeutic drugs that prevent uncontrolled cell division processes in the last century, many studies are still being carried out to develop drugs with higher anticancer efficacy and lower level of side effects. Herein, we designed, synthesized, and characterized six novel coumarin-triazole hybrids, and evaluated for anticancer activity of the one with the highest potential against the breast cancer cell line, MCF-7 and human cervical cancer cell line, human cervical adenocarcinoma (HeLa). Compound 21 which was the coumarin derivative including phenyl substituent with the lowest IC50 value displayed the highest cytotoxicity against the studied cancer cell line. Furthermore, the potential use of poly (lactic-co-glycolic acid) nanoparticles (PLGA NPs) prepared by the emulsifying solvent evaporation method as a platform for a drug delivery system was studied on a selected coumarin derivative 21. This coumarin derivative-loaded PLGA NPs were produced with an average size of 225.90 ± 2.96 nm, −16.90 ± 0.85 mV zeta potential, and 4.12 ± 0.90% drug loading capacity. The obtained 21-loaded PLGA nanoparticles were analyzed spectroscopically and microscopically with FT-IR, UV–vis, and scanning electron microscopy as well as thermogravimetric analysis, Raman, and x-ray diffraction. The in vitro release of 21 from the nanoparticles exhibited a controlled release profile just over one month following a burst release in the initial six hours and in addition to this a total release ratio of %50 and %85 were obtained at pH 7.4 and 5.5, respectively. 21-loaded PLGA nanoparticles displayed remarkably effective anticancer activity than 21. The IC50 values were determined as IC50 (21-loaded PLGA nanoparticles): 0.42 ± 0.01 mg ml−1 and IC50 (free 21 molecule): 5.74 ± 3.82 mg ml−1 against MCF-7 cells, and as IC50 (21-loaded PLGA nanoparticles): 0.77 ± 0.12 mg ml−1 and IC50 (free 21 molecule): 1.32 ± 0.31 mg ml−1 against HeLa cells after the incubation period of 24 h. Our findings indicated that triazole-substituted coumarins may be used as an anticancer agent by integrating them into a polymeric drug delivery system providing improved drug loading and effective controlled drug release.
Time-helicity de-resonation (T-H) diagram for energy-selective mixing of charged particles during sawtooth crashes in tokamaks
Authors: Bierwage A , Lauber Ph , Shinohara K
Published: April 2024

It was recently shown that there exists a narrow parameter window where benign sawtooth crashes cause only mixing of bulk plasma and slowed-down alpha particle ‘ash’, while leaving MeV-class fast alphas largely unperturbed (Bierwage et al 2022 Nat. Commun.
13 3941). Here, we revisit the underlying physical picture and reframe it in a manner that may be suitable for systematic analyses of this phenomenon in modeling, simulation and experimental studies. In particular, we propose a graph that we call ‘time-helicity de-resonation diagram’ (short: T-H diagram) that captures the physical essence of energy-selectivity of sawtooth-particle interactions and visualizes it in a compact, intuitive way. Moreover, the regimes of good confinement and strong mixing during a sawtooth crash can be discerned via a single figure of merit: the T-H radius. The concept is introduced here on the basis of simulation results and would eventually benefit from further validation when applied to suitable empirical data.
Surface recombination in Pyrex in oxygen DC glow discharges: mesoscopic modelling and comparison with experiments
Authors: Viegas Pedro , Silveira Jorge , Cunha Dias Tiago , Guaitella Olivier , Sofía Morillo Candás Ana , Guerra Vasco
Published: April 2024

Surface recombination in an oxygen DC glow discharge in a Pyrex (borosilicate glass) tube is studied via mesoscopic modelling and comparison with measurements of recombination probability. A total of 106 experimental conditions are assessed, with discharge current varying between 10 and 40 mA, pressure values ranging between 0.75 and 10 Torr, and fixed outer wall temperatures (

T

w

) of −20, 5, 25 and

50

∘

C

. The model includes O+O and O+O2 surface recombination reactions and a

T

w

dependent desorption frequency. The model is validated for all the 106 studied conditions and intends to have predictive capabilities. The analysis of the simulation results highlights that for

T

w

=
−
20

∘

C

and

T

w

=
5

∘

C

the dominant recombination mechanisms involve physisorbed oxygen atoms (

O
F

) in Langmuir–Hinshelwood (L-H) recombination

O
F

+

O
F

and in Eley–Rideal (E-R) recombination

O
2

+

O
F

, while for

T

w

=
25

∘

C

and

T

w

=
50

∘

C

processes involving chemisorbed oxygen atoms (

O
S

) in E-R

O
+

O
S

and L-H

O
F

+

O
S

also play a relevant role. A discussion is taken on the relevant recombination mechanisms and on ozone wall production, with relevance for higher pressure regimes.
The spindle approximation of network epidemiological modeling
Authors: Mou Jianhong , Dai Bitao , Tan Suoyi , Holme Petter , Lehmann Sune , Liljeros Fredrik , Lu Xin
Published: April 2024

Understanding the dynamics of spreading and diffusion on networks is of critical importance for a variety of processes in real life. However, predicting the temporal evolution of diffusion on networks remains challenging as the process is shaped by network topology, spreading non-linearities, and heterogeneous adaptation behavior. In this study, we propose the ‘spindle vector’, a new network topological feature, which shapes nodes according to the distance from the root node. The spindle vector captures the relative order of nodes in diffusion propagation, thus allowing us to approximate the spatiotemporal evolution of diffusion dynamics on networks. The approximation simplifies the detailed connections of node pairs by only focusing on the nodal count within individual layers and the interlayer connections, seeking a compromise between efficiency and complexity. Through experiments on various networks, we show that our method outperforms the state-of-the-art on BA networks with an average improvement of 38.6% on the mean absolute error. Additionally, the predictive accuracy of our method exhibits a notable convergence with the pairwise approximation approach with the increasing presence of quadrangles and pentagons in WS networks. The new metric provides a general and computationally efficient approach to predict network diffusion problems and is of potential for a large range of network applications.
Spot scanning imaging calibration method based on deviation model for wafer inspection
Authors: Qu Dingjun , Zhou Zuoda , Li Zhiwei , Ding Ruizhe , Jin Wei , Ru Yu , Zhu Xiahanxiao , Luo Haiyan , Xiong Wei
Published: April 2024

The spot scanning defect detection system has good detection performance for wafer defects. However, due to the existence of system assembly errors, the wafer defect inspection system could not scan following the planned trace, which resulted in distortion of the reconstructed image and had a greater impact on defect feature extraction and accurate defect location. The system deviation calibration and adjustment can further facilitate the accuracy of the system position and image reconstruction. To address this issue, the causes and shapes of imaging distortion were analyzed and simulated, and a simple and effective calibration method based on a scanning deviation model for the spot scanning defect detection system was proposed. First, a scanning deviation model was established following the characteristics of the spot scanning system, and different degrees of reconstructed image distortion were simulated and analyzed as the system deviation changes. Then, an 8-inch wafer with a grid was used as the calibrator and scanned using the developed spot scanning system. Serveral grid corners in the reconstructed image are selected and used as the calibration feature points. The constraint function is constructed using the equidistant features between adjacent grid points, and then the quasi-Newton method is used to optimize the parameters of the function to obtain the best deviation estimation of the spot scanning system. To prove the validity of the estimated deviation parameters, another patterned wafer was scanned and the distortion image was used for reconstruction. The experiment demonstrated that an accurate and distortion-free wafer image can be reconstructed using the calibrated deviation parameters, and the root mean square error of the measured distance between two points of interest was only 0.61 pixels, which proved the effectiveness of the proposed calibration method.
Analytic solutions of Eliashberg gap equations at superconducting critical temperature
Authors: Pinsook Udomsilp , Natkunlaphat Nattawut , Rientong Komkrit , Tasee Pakin , Seeyangnok Jakkapat
Published: April 2024

We perform simple mathematical analysis of the Eliashberg gap equations, and derive the analytic expression at the superconducting critical temperature. In order to perform exact summation of

L

T

c

=

∑

λ

m
1

2
m
−
1

,

we use the Einstein and Debye models for the Eliashberg spectral function. This quantity is in good agreement with data derived from experimental and DFT data. To the leading-term approximation, the analytic expression of the superconducting critical temperature is of the form

T

c

=

2

e

γ
−
1

π

ω

x

exp

−

1
+

μ

*

ln

4

e

γ

m

c

λ

,

where

ω

x

=

ω

2

or

ω

ln

.

The frequencies

ω

2

and

ω

ln

come out naturally from the models. These equations contain

m

c

as an adjustable parameter. There are no other free parameters and no empirical formula involved. We compare the results of these equations with the celebrated Allen-Dynes modified McMillan equation together with the data from experiments and DFT calculations. The data show strong correlation between our analytic expression and the celebrated Allen-Dynes equation.
Study on repeated discharge frequency characteristics of plasma pulse equipment
Authors: Kang Zhongjian , Dong Zhentao , Zheng Shichao , Shen Yichao , Liu Peng , Gong Dajian , Du Haoran , Hu Caifu
Published: April 2024

In order to increase the production of unconventional oil and gas, it is necessary to improve its reservoir. Plasma pulse technology is one of a safe and environmentally friendly reservoir reconstruction technology. In this paper, the discharge test of plasma pulse equipment was carried out in the laboratory. The different discharge stages (pre-discharge, main-discharge, sinusoidal attenuation oscillation and post-discharge stage) of plasma pulse equipment in a single discharge were discussed, and the frequency characteristics in the repeated discharge were studied in detail. The discharge test shows that the energy and average power of main-discharge stage are about 109 J and 15.6 MW respectively, and the discharge frequency range is about 0–25 Hz. Furthermore, the linear attenuation function model of breakdown voltage change under the initial discharge frequency of 4 Hz, 9 Hz, 14 Hz and 19 Hz is established, and the change law of breakdown voltage decreases linearly with the increase of discharge frequency is revealed. The results show that the research content of this paper has an important guiding significance for revealing the variation law of repeated discharge frequency characteristics of plasma pulse equipment, which is helpful to further optimize the design of plasma pulse equipment and improve its working performance.
Study of structural, dynamical stability, electronic magnetic and optical properties of RbSnO3 oxide perovskite compound using the density functional theory approach
Authors: Boualleg Cheyma , Meddour Athmane , Gous Mohammed Hadi
Published: April 2024

This study investigates the structural, phonon, elastic, electronic, magnetic and optical properties of cubic perovskite RbSnO3. The calculations are based on the linearized augmented plane wave method with total potential (FP-LAPW), implemented in the Wien2k code; two approximations are used for calculate properties, PBE-GGA and TB-mBJ . The values of the tolerance factor and the formation energy of this material indicate that it is stable in the cubic structure of Pm3̅m symmetry. The Born criteria for the compound under study confirm its mechanical stability, while its phonon dispersion curves confirm its dynamic stability. The results of the electronic and magnetic properties show that the compound is ferromagnetic (FM) semi-metallic (DM) with semiconductor behavior in the majority spin channel and with an indirect gap in the M → Γ direction and having a total magnetic moment equal to 1 μB and a Curie temperature equal to 527 K. Optical spectra of the compound show high optical conductivity in the infrared region and towards the end of the spectrum at around 6 eV, high reflection in the infrared region with a maximum at 0.25 eV, and high absorption in the ultraviolet region at 6 eV. In view of these results, the RbSnO3 perovskite can be a promising candidate for spintronics applications as it can be used in optical devices working in the ultraviolet (UV) light region.
Dirac stars in wormhole spacetime
Authors: Hao Chen-Hao , Sun Shi-Xian , Huang Long-Xing , Zhang Rong , Su Xin , Wang Yong-Qiang
Published: April 2024

In this paper, we study the spherically symmetric Dirac star model in the presence of a phantom field, obtaining a traversable wormhole solution in non-trivial topological spacetime. This solution exhibits asymmetry in both the field configuration and the metric and possesses a finite ADM mass M and Noether charge Q. Furthermore, due to a wormhole at the center, this solution exhibits many differences from the Dirac star under trivial spacetime. Notably, when the wormhole throat size is small, our numerical calculations indicate the emergence of an extremely approximate black hole solution on one side of the wormhole spacetime, a phenomenon unexplored. At this time, the Kretschmann scalar near the throat tends to infinity, indicating the wormhole becomes untraversable.
Performance optimization of a SERF atomic magnetometer based on flat-top light beam
Authors: Yuan 袁 Ziqi 子琪 , Tang 唐 Junjian 钧剑 , Lin 林 Shudong 树东 , Zhai 翟 Yueyang 跃阳
Published: April 2024

We explore the impact of pumping beams with different transverse intensity profiles on the performance of the spin-exchange relaxation-free (SERF) atomic magnetometers (AMs). We conduct experiments comparing the traditional Gaussian optically-pumped AM with that utilizing the flat-top optically-pumped (FTOP) method. Our findings reveal that the FTOP-based approach outperforms the conventional method, exhibiting a larger response, a narrower magnetic resonance linewidth, and a superior low-frequency noise performance. Specifically, the use of FTOP method leads to a 16% enhancement in average sensitivity within 1 Hz–30 Hz frequency range. Our research emphasizes the significance of achieving transverse polarization uniformity in AMs, providing insights for future optimization efforts and sensitivity improvements in miniaturized magnetometers.
Periapsis shift in spherically symmetric spacetimes and effects of electric interactions*
Authors: Wang 王 Qianchuan 乾川 , Jia 贾 Junji 俊基
Published: April 2024

The periapsis shift of charged test particles in arbitrary static and spherically symmetric charged spacetimes are studied. Two perturbative methods, the near-circular approximation and post-Newtonian methods, are developed and shown to be very accurate when the results are determined to high orders. The near-circular approximation method is more precise when eccentricity e of the orbit is small, whereas the post-Newtonian method is more effective when orbit semilatus rectum p is large. Results from these two methods are shown to agree when both e is small and p is large. These results are then applied to the Reissner-Nordström spacetime, the Einstein-Maxwell-dilation gravity, and a charged wormhole spacetime. The effects of various parameters on the periapsis shift, particularly that of the electrostatic interaction, are carefully studied. The periapsis shift data of the solar-Mercury are then used to constrain the charges of the Sun and Mercury, and the data of the Sgr A*-S2 periapsis shift are used to determine, for the first time using this method, the constraints of the charges of Sgr A* and S2.
Analysis of the Effect of Distillation Parameters on Freshwater Yield in Seawater Dispenser
Authors: Koswara E , Nasim  , Rahmanudin F
Published: April 2024

The purpose of this study is to analyze the process of condensation that occurs in the condenser in the seawater distillation dispenser system. In the seawater dispenser system, it has been tested using the default system from the existing dispenser. The test results from the seawater distillation dispenser can change seawater with a seawater content of 20% to 0%. Initial testing was carried out only to see whether the built-in dispenser system with the addition of a 1-level condenser system could work well or not. Therefore, it is necessary to analyze the condensation process that occurs in the condenser to see how efficiently the condenser works. The method used is by testing directly on the seawater distillation dispenser system. The test was carried out in 3 stages, each of which used a volume of 400 mL of seawater. The capacity refers to the volume available in the sea-water distillation dispenser reactor. The results obtained from the tests carried out are in the form of the time required for the freshwater production process, the amount of fresh water produced and the condenser temperature that occurs. This research is important to see the performance of the distillation dispenser system. In previous tests it has not been seen how efficient the system has been made. by testing the seawater distillation dispenser system, you can see how efficient the tool is and how the operating parameters occur. Fresh water production in stage 1 condenser starts to appear at 350 seconds (6 minutes first). The maximum production of fresh water is 24.6 mL (6.15%) of the total 400 ml. The average condenser temperature is above 80°C.
Analysis of Solar Water Heater with Modification Absorber Plate Integrated Thermal Storage
Authors: Rahmadhani M A I , Jalaluddin  , Mochtar A A
Published: April 2024

In various countries worldwide, solar water heater systems (SWHs) are utilized as devices that harness solar energy as a primary energy source. This study investigates the performance of SWHs numerical simulation by integrating phase change material (PCM) paraffin wax onto an absorber plate collector at the bottom for thermal storage. This study presents the thermal performance of a SWHs that uses an absorber plate with PCM for thermal energy storage. In this test, four variations of the model tested, namely a) standard flat plate (SFP), b) standard flat plate with PCM storage thickness 10mm (SFP+PCM 10mm), c) standard flat plate with PCM storage thickness 7mm (SFP+PCM 7mm), and d) standard flat plate with PCM storage thickness 4mm (SFP+PCM 4mm), were investigated using numerical simulation. Initially, an analytical investigation was conducted to examine the material qualities of paraffin wax utilised for phase change material (PCM) storage. The SWH systems were subsequently imported and simulated under three different levels of continuous solar radiation: 400 W/m2 700 W/m2 and 1000 W/m2. The simulation incorporates the use of computational fluid dynamics (CFD) tools. The results of the study revealed that the collector of the SWH system, which utilised an absorber plate containing phase change material (PCM) storage, demonstrated exceptional performance. Models with a thickness of 7mm PCM or SFP+PCM 7mm have the highest efficiency compared to other models with an efficiency value of 64%. There is a 3-4% increase in efficiency with variations in models that use PCM thermal storage compared to models that do not use PCM thermal storage.
Equilibrium Volumetric Experiment Apparatus Review for Mixed-Gas Adsorption
Authors: Huwae R , Nuriyadi M , Tjiptadi AT. , Nasruddin
Published: April 2024

This research aim is to identify the additional equipment and system functions required to set up an experimental system for mixed-gas dynamic adsorption using equilibrium volumetric technique. As well as to review the process variables’ effect on adsorption capability, while using an experimental system apparatus consisting of an equipment previously mentioned in selected papers. In this study, the selected experimental research on mixed-gas adsorption is reviewed, which used the equilibrium volumetric method. The relationship between process variables and adsorption capacity, kinetics, and diffusional mass transfer are observed. The correlation between adsorbate concentration, adsorption temperature, pressure during adsorption process, flow rate of adsorbate and adsorption capacity indicates that using additional equipment in the experimental mixed-gas dynamic adsorption is feasible. The correlation between these parameters is in agreement with common understanding of adsorption. The predicted adsorption capacity and analysis of kinetics adsorption are consistent with the model. The diffusional mass transfer could explain a diffusional step of the adsorbate onto the adsorbent.
Experimental Study on Flame Merging Phenomenon
Authors: Famaretha S D , Santoso M A , Nugroho Y S
Published: April 2024

No less than 350 housing fires happened each year during 2016-2021 in DKI Jakarta. Fatality is fortunately not a common issue, but it was predicted that 200 billion rupiahs losses annually from the fires. Narrow spaces with a bulk of people housing make the fire spread faster. Fire burns, whichever is the ‘ready-to-burn’ first, so it cannot be expected one house is already burned out first, then the fire will continue to the next house. From this phenomenon, it potentially has more than one hotspot from the fire that can grow bigger with a flame merging situation. For a better understanding of fire merging phenomenon, experimental study was reported in this work. The study was conducted on a laboratory scale experiment with the variation of the separation distance between the fire sources. The separation distance was set to be 0; 5; 10 cm. The fire source was shredded paper which is placed in cylindrical baskets having diameters of 5 cm, 10 cm, and 15 cm. The experimental data were recorded by using K-type thermocouple, visual and thermal cameras, and a scale. The results show that the probability of flame merging increases with the diameter of baskets. The temperature and flame height increase as the flame merging phenomenon occurs. However, flame merging does not have a direct impact on combustion efficiency based on this experiment.
Biodiesel Production Process Using Plasma Method on Engine Performance and Exhaust Gas Emissions
Authors: Azis N , Amaliyah N , Putra A E E , Kusumawati D , Aldi M
Published: April 2024

Crude Palm Oil is one of the renewable energy sources that is widely used as an environmentally friendly energy source, one form of utilization is by processing crude palm oil into biodiesel. However, biodiesel has drawbacks in terms of performance which is less good than fossil fuels. This study aims to improve the performance of the engine produced by biodiesel and maximize the utilization of crude palm oil in biodiesel. In improving the performance of diesel engines, the treatment method used in producing biodiesel affects the physical properties of the biodiesel produced. This study uses a mixture of Dexlite fuel with plasma biodiesel in a ratio of 1:1, which produces B50 biodiesel. To measure the performance using a TV1 diesel engine and a gas analyzer OPA 100 with a compression ratio of 1:18, 1:14, and a load of 1 kg, 3 kg, 5 kg, 7 kg, and 9 kg. The results showed that the maximum effective power (BP) occurred at a load of 9 kg with a ratio of 1: 14, which was 2.38 kW, and the minimum specific fuel consumption (SFC) occurred at a compression ratio of 1: 18 and loading 9 which is 0.240 Kg/kWh, the maximum volumetric efficiency (ηvo) occurs at 9 kg loading with a compression ratio of 1: 14 with the addition of 0% methanol solvent which is 70.61%, and thermal efficiency (ηth) maximum loading occurred at 9 kg loading with a compression ratio of 1: 18 using 0% methanol solvent, which is 44,74%.
The Effect of Welding Process Parameters on the nilon-6 Plate Friction Stir Welded Joint
Authors: Nugroho A W , Aulistianto I , Budiyantoro C
Published: April 2024

Nylon-6 is one of the most extensively used engineering thermoplastics. Due to its durability, reduced weight, low coefficient of friction, and abrasion resistance, this polymer is an excellent substitute for various materials, including metals and rubber. Despite being those, nylon-6 materials are joined together utilizing multiple welding processes. The current work examined the viability of the friction stir welding (FSW) method on nylon 6 plates that were 4 mm thick to investigate the effect of tool diameter ratio and feed rate on nylon-6 sheets with the FSW method on the tensile properties of the joints. The 4 mm thickness of the nylon-6 plate was cut into the dimensions of 115 mm x 100 mm. The sliced plates were then joined through the FSW process using ST80-based tools with various parameters in the shoulder to pin diameter ratio (D/r ratio) of 10/3, 15/3, and 20/3 and feed rates (FR) of 4 mm/minute, 6 mm/minute, and 8 mm/minute at a rotational speed (RS) of 5800 RPM. Afterward, the weld joint is cut using water jet cutting according to the tensile testing standard ASTM D638 type IV. Following this, characterization of the speci-mens, including macrograph examination, hardness testing, and tensile testing, was carried out. The results show that the highest tensile strength was obtained at a tool diameter ratio of 10/3 mm with a feed rate of 6 mm/minute, with a tensile strength value of 19 MPa reaching up to circa 90% of joint efficiency. The strength of the welded joint then decreases as the diameter ratio of the tool increases with each feed rate. Some defects appeared at the higher tool diameter ratios welded joint, including incomplete fusion, flash, thinning, and lack of bonding. In conclusision the combination of a D/d ratio of 10/3 and a FR of 6 mm/min at RS 5800 RPM can provide the optimal conditions for a strong nylon-6 friction stir welded joint.
Analysis of 3D-Printing Layer Height Pattern Effect to ADC12’s Mechanical Properties Investment Casting Results
Authors: Suprapto W , Irawan Y S , Auliasyah P
Published: April 2024

This study aims to determine the mechanical properties, both hardness and tensile strength of investment casting results from 3D-Printing patterns. In this analysis, the aluminum scrap comes from the piston and will later be Die Casted and become ADC 12. The pattern used Poly Lactid Acid material, then the pattern is printed with varying layer height. After that, analysis was carried out using experimental for surface roughness and hardness of ADC12. The Hardness value is used to get the Tensile strength of ADC12 from empirical aproach. The results of the analysis show that the hardness and tensile strength of the ADC12 casting investment product have decreased due to the increasing value of the surface roughness of the cast product which is influenced by the use of a larger layer thickness.
Effect of Austempering Holding Time Variations of 30, 60, and 90 Minutes at 300 °C on The Microstructure and Toughness of Nodular Cast Iron
Authors: Darmawan A S , Anggono A D , Yulianto A , Febriantoko B W , Hamid A
Published: April 2024

The phases of the nodular cast iron matrix are similar to those of steel. Therefore, heat treatment of steel can be applied to nodular cast iron. A potential heat treatment for nodular cast iron is austempering. This study aimed to determine the effect of austempering holding time at 300 °C on the microstructure and toughness of nodular cast iron. The austempering process begins with austenitizing at a temperature of 850 °C for 60 minutes, then the quenching process is carried out in a salt bath until a temperature of 300 °C is held with variations of 30, 60, and 90 minutes, then cooled to room temperature. Metallographic testing was conducted to determine the phase change before and after the austempering process using a Scanning Electron Microscope (SEM). Meanwhile, impact testing was carried out to determine changes in toughness before and after the austempering process. At a holding time of 30 minutes, metallographic testing on the raw material produced a gray coarse pearlite phase, black nodular graphite surrounded by white ferrite. After the austempering process, gray fine pearlite and black nodular graphite appeared. At the holding time of 60 and 90 minutes, the graphite sizes were bigger. Austempering withholding times of 30, 60, and 90 minutes resulted in impact energy of 4.2, 10, and 11 Joule. From the results of the study, it was concluded that an increase in holding time would increase the size of the graphite and the toughness of nodular cast iron.
Study on Resin-based 3D Printed Product for Spin Casting Mold Making
Authors: Risdiyono
Published: April 2024

Spin casting (centrifugal rubber mold casting) is well known process to produce castings by utilizing inertia. A vulcanized rubber mold is typically used by spinning it at an optimum speed along its central axis. There are many factors influence the quality of casting product, including the quality of mold, the temperature of molten material, the speed and duration of rotation, as well as the pressure upon the mold. This research aims to investigate the quality of casting product when a resin-based 3D printing is utilized to make a model for vulcanized rubber mold. The model is designed by using CAD software and printed layer by layer by using Selective Laser Sintering (SLS) method. Curing process is employed in order to harden the model before placed in the disc-shape silicone rubber. The rubber is then vulcanized so that the mold is formed. Standard edge gate and straight runner are then made to let the molten material flow during casting process. Zinc alloy is used as raw material in the casting process with five variations of rotation speed. Based on the experiment results it is observed that the resin-based 3D printed product can be used as a master model in rubber mold making with some limitations. The resin could not maintain its shape due to the high temperature and pressure during vulcanization process. However, for simple design without any need of very small and detail features, the resin-based 3D printed product still can be used as an alternative.
Ramie Fiber Woven Composite: The Effect of Number of Layers of Woven Fibers on the Thrust Force in the Drilling Process
Authors: Djafar Z , Azis N , Djafar Z
Published: April 2024

Composite material is a combination of two or more materials to obtain better properties and capabilities of the constituent materials. Applications for the use of composites can now be found in industrial equipment to household appliances. To produce these products required machining process. The aim of the study was to determine the effect of the number of layers of woven fiber and the diameter of the drill bit on the thrust of the ramie woven fiber composite in the machining process. The research method was based on ASTM D 5766/D 5766M-02 (Standard Test Method for Tensile Strength Open Hole Laminated Polymer Matrix Composites), the method of making composite material specimens using the hand lay-up method, and the drilling process was carried out with various machining parameters such as composite thickness with variations of 3 layers, 4 layers, 5 layers, and without layers (0 layers). The maximum thrust value obtained was 153.54 ± 3.3 N, with 5 layers of hemp fiber reinforcement, the highest feed rate was 0.15 mm/rev, and the lowest spindle speed was 88 rpm, while the minimum thrust value was 29.52. ± 3.12 N with 0 layers of ramie fiber reinforcement, and the lowest feed rate is 0.05 mm/rev with the highest spindle speed of 1500 rpm.