bluuebunny/crossref_metadata_2025 huggingface dataset:
Are the global economic policy uncertainties blocking the export flows of emerging markets? A heterogeneous panel SVAR analysis
Authors: Aslan Caglayan , Acikgoz Senay
Published: April 2023

Purpose – This paper examines the effect of global economic policy uncertainty (EPU) on emerging markets (EMs) export flows.
Methods – This paper uses a structural panel vector autoregression modeling approach to capture country interdependencies and the likelihood that EMs’ responses are heterogeneous and dynamic. An unbalanced monthly panel data from 2003:01 to 2019:12 is used to estimate impulse responses and variance decompositions not only for the entire panel data but also for each EM.
Findings – The results show that global EPU has a persistent and negative effect on exports, while foreign income and the exchange rate increase export volumes in EMs. Given the different responses of EMs to uncertainty shocks, the second-stage regression estimates suggest that greater sectoral export diversification in an EM can potentially reduce the unfavorable impact of global EPU on their export flows. Meanwhile, the higher technology content of exports leads to a multiplication of global EPU transmissions.
Implication – These findings advance the literature by highlighting the importance of accounting for the transmission effect of global EPU in EMs by considering country heterogeneity.
Originality – This is the sole paper examining the factors that mitigate or amplify GEPU impacts on export flows by estimating second-step ordinary least square equations.
Green Synthesis of Silver Nanoparticles via Cratoxylum glaucum Leaf Extract Loaded Polyvinyl Alcohol and Its Antibacterial Acitvity
Authors: Fabiani Verry Andre , Lingga Rahmad
Published: April 2023

In this study, green synthesis of silver nanoparticles via Cratoxylum glaucum leaf extracts loaded with polyvinyl alcohol and its bacterial activity were tested. Nanosilver from ‘Pucuk Idat’ leaves has a non-uniform size and tends to agglomerate, making the nanoparticle size unstable and challenging to apply further. Therefore, so that nanoparticles do not aggregate, efforts are made to add stabilizers. Polyvinyl alcohol (PVA) is a polymer that can be used as a stabilizer because it can prevent unwanted aggregation and oxidation processes. UV-Vis analysis results show that PVA as a stabilizer can avoid an increase in wavelength shift. Based on the results of this XRD analysis, it can be concluded that in this research sample, the silver nanoparticle is formed with a cubic crystal system, and it can be observed that the smallest average particle size is in the 0.75% Ag/PVA sample of 10.32 nm. Furthermore, based on the antibacterial test against E. coli and S. aureus, it can be explained that the 0.75% PVA-modified nanosilver sample showed weak to medium antibacterial activity.

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Recovery of Valuable Metals from Fly Ash via Hydrometallurgy Method for Li-ion Battery Anode Material
Authors: Yudha Cornelius Satria , Apriliyani Enni , Paramitha Tika , Suci Windhu Griyasti , Gustiana Himmah Sekar Eka Ayu
Published: April 2023

Coal-derived fly ash, or CFA, is a harmful waste for humans. CFA waste handling by its processing and utilization has become the most promising approach, which not only decreases the waste's hazard level but also improves its economic potential. This research aims to recover metals from CFA and utilize them as anode material for Li-ion batteries. Iron, magnesium, aluminum, and calcium are retrieved from the CFA via a two-step hydrometallurgical method, i.e., acid leaching followed by alkaline precipitation. The leaching process utilizes various acids, such as acetic acid (CH3COOH), hydrochloric acid (HCl) and sulfuric acid (H2SO4). Metal precipitation is carried out using sodium hydroxide solution (NaOH). Morphological and quantitative metal composition analysis are investigated using a scanning electron microscope and energy dispersive spectroscopy (SEM-EDX). The physical and chemical properties of the as-prepared samples are characterized using Fourier-transformed Infra-red spectroscopy (FTIR) and Thermal Gravimetry-Differential Thermal Analysis (TG/DTA). Based on the analysis, iron, magnesium and calcium are successfully recovered in a mixed hydroxide precipitate. The type of acid affects the final morphology and composition of the product. Therefore, our approach can be considered effective in CFA waste processing and producing high-quality product.
The Adsorption Performance and Characterization of Activated Charcoal of Bone Char Against Acid Orange 7
Authors: Fatimah Siti , Azinuddin Yazid Rijal
Published: April 2023

The use of Acid Orange 7, a synthetic dye, in the textile industry harms the environment because it is carcinogenic. This research aims to remove the Acid Orange 7 dye dissolved in the water. This study used cow bone charcoal as an alternative adsorbent made by the carbonization method. In addition, the batch adsorption method was applied in the bleaching process of the synthetic dye waste, Acid Orange 7. Several tests, such as SEM, EDX, BET, XRD, and FTIR, were carried out to determine the characteristics and ability of activated charcoal from cow bones as an adsorbent for acid Orange 7 dye waste. Other organic adsorbents, such as graphene oxide and activated carbon, were used to compare the results. Bone char adsorption Acid Orange 7 62.2% efficiently. The adsorption efficiency of activated carbon is 79.8%, while graphene oxide has an adsorption rate of 89.4%. The findings revealed that bone char could be used to cure synthetic dye waste, Acid Orange 7, as an alternative. Additional treatment 
Pendampingan dan Pengenalan Kurikulum Merdeka Bagi Guru
Authors: Camellia Camellia , Alfiandra Alfiandra , El Faisal Emil , Setiyowati Rini , Sukma Ulya Rosidafi
Published: April 2023

Kegiatan pengabdian kepada masyarakat ini bertujuan untuk memberikan pengetahuan kepada guru di kabupaten Ogan Ilir mengenai kurikulum merdeka. Sasaran kegiatan ini yaitu guru yang aktif mengajar di SMPN 1 Indralaya dan guru MGMP PPKn SMP Ogan Ilir. Kegiatan diawali dengan memberikan pretest untuk mengukur pengetahuan awal guru mengenai kurikulum merdeka, kemudian dilanjutkan dengan pemaparan materi terkait kurikulum merdeka. Kegiatan dilanjutkan dengan pemberian posttest untuk melihat peningkatan pengetahuan guru mengenai kurikulum merdeka. Nilai rata-rata Post yang diperoleh guru yaitu 57 dan nilai rata-rata posttest adalah 73 dimana terdapat peningkatan sebesar 0,16%. Kegiatan pengabdian kepada masyarakat diakhiri dengan pendampingan penyusunan rencana pelaksanaan pembelajaran dimana guru diminta membuat produk berupa modul ajar yang sesuai dengan kurikulum merdeka. Berdasarkan produk yang dibuat oleh guru diketahui bahwa 80% guru yang mengikuti kegiatan sudah bisa membuat modul ajar dengan baik.
Sosialisasi Peningkatan Partisipasi Perempuan Dalam Pembangunan Desa Cisaat
Authors: Syafrudin Iqbal , Asep Rudi Casmana  , M. Fajar Sae
Published: April 2023

Pembahasan artikel ini memiliki tujuan untuk memberikan pemahaman kepada masyarakat tentang pentingnya partisipasi masyarakat khususnya kaum perempuan dalam pembangunan desa, memberikan pemahaman tentang posisi masyarakat dalam pembangunan serta contoh-contoh partisipasi yang dapat dilakukan masyarakat dalam pembangunan. Permasalahan yang muncul yaitu masih rendahnya tingkat partisipasi perempuan dalam pembangunan desa mitra serta masih banyak masyarakat yang belum tahu harus berpikir dan bertbuat apa untuk membangun desa. Untuk permasalahan tersebut kolaboratif yang akan dilaksanakan oleh pengusul bersama mitra yaitu kegiatan sosialisasi dengan membawakan materi tentang pentingnya partisipasi masyarakat khususnya kaum perempuan dalam membangun desa serta memberikan contoh-contoh partisipasi yang dapat dilakukan untuk membangun desa mitra. Metode yang digunakan dalam melakukan pengabdian masyarakat ini yaitu dengan pendekatan kolaboratif antara pengusul dengan mitra. Program kegiataan pengabdiaan masyarakat ini diisi dengan kegitan penyuluhan dan diskusi mengenai pentingnya partispasi perempuan dalam pembangunan desa serta peningkatan kemampuan komunikasi warga desa Cisaat, yang mana dua materi tersebut dirasa salling berkesinambungan serta bisa mendukung kemajuan desa Cisaat dengan tidak melupakan partisipasi dari perempuan. Adapun materi tentang pentingnya partisipasi perempuan dalam pembangunan desa dibawakan oleh Iqbal Syafrudin dan materi tentang peningkatan kemampuan komunikasi masyarakat desa Cisaat yang disampaikan oleh Asep Rudi Casmana.
One Village One Development: A Government Concept in The Development of The Tourism Sector in Batu City
Authors: Ratuloly Rudy , Rifa’i Muhamad , Hardianto Willy Tri
Published: April 2023

Tourism is an action or a movement produced by someone or something that goes from one location to another repeatedly for a while with the aim of enjoying the beauty of nature and without generating enough money to pay the cost. This study is expected to decide and break up the work of public authorities and the community in developing the travel industry in Batu City. This study uses an interesting subjective exploration. Determination of research informants are Tourism and Marketing Product Development Staff, Staff of Control Analysis and Reporting of development planners and staff of the Head of Planning. Data collection techniques are interviews, documentation, observation. Data analysis through the process of triangulation. Based on the results of this study, the role of the Batu City government has been very good in developing the existing tourism potential in the villages in Batu City itself because in terms of physical aspects, attractions, accessibility, activities and facilities as well as socio-economics have been very good and supportive for developing tourism where the government's role is carried out properly as carried out by the Tourism Office, the Bapplitbangda Service and the village government which is under the auspices of Batu City itself by carrying out tasks such as providing training to local communities and the Bapplitbangda Service providing good infrastructure facilities and village apparatus who develop existing excursions so that with good tourism development it can attract visitors to visit these vacation spots and greatly impact on increasing PAD by utilizing existing natural potential.
The Effectiveness of the Thumb Sakera Program in Pasuruan Regency
Authors: Mursyidah Lailul , Rodiyah Isnaini , Agustina Isna Fitria , Setiawan Ikhsan , Rustianingsih Eni
Published: April 2023

The Office of Family Planning and Women's Empowerment created an innovation to reduce the number of women's violence in Pasuruan Regency. The program is the Thumb Sakera program (Aware of the Violence of Women and Children by Picking Up Balls). The purpose of this study was to describe and analyze the innovation of the Thumb Sakera program (Aware of the Violence of Women and Children by Picking Up Balls) in Pasuruan Regency. This study uses a quantitative descriptive. The sample of this research is 32 people. Data processing techniques use statistical analysis which consists of grouping data based on respondents, tabulating data based on all respondents, presenting data according to research results, and carrying out calculations to answer the problem formulation. The analysis technique used is the Likert scale technique. The results of the validity test of this study showed that Cronbach's Alpha was above 0.6 which means that each item was declared valid. In addition, the reliability test of 12 items shows a strong reliability with Cronbach's Alpha 0.764. It can be identified that the results of the research on the effectiveness of the Thumb Sakera program in Pasuruan Regency are in the "Effective" category. The average value is 78.59% which is obtained from the determination indicator; program target of 82.29%; program socialization of 75.84%; program objectives of 79.59; and program monitoring of 76.67%.
Modified p-y curves for monopile foundation with different length-to-diameter ratio
Authors: Wang Bin , Jiao Yuqi , Qiao Dongsheng , Gao Shan , Li Tianfei , Ou Jinping
Published: April 2023

The soil reaction of the monopile foundation subjected to lateral loading in offshore wind turbines is typically assessed relying on p-y curves advocated by API. However, this method is inadequate for gradually increasing monopile diameters and significantly underestimates the lateral soil confinement. In the present works, a 3D pile-soil interaction finite element model was first established, considering the soil suction and strain hardening characteristics for the normally consolidated clay in China’s sea. Modifications to the p-y curves in API were accomplished in the comparative process between the lateral soil resistance-displacement curves retrieved from the finite element model and the representative expression. Furthermore, the prediction accuracy for the corrected p-y curves has been proved by forecasting the monopile lateral bearing capacity with varying length-to-diameter ratios, which also demonstrates that the modified p-y curves could successfully reflect the lateral soil confinement of the normally consolidated clay and flexible piles. It also provides an approach to assess the deformation response and horizontal ultimate bearing capacity of monopiles with different length-to-diameter ratios.
Phenotypic polymorphism of leaves among the populations of Moroccan chestnut (Castanea sativa Mill.)
Authors: Toujgani Ihssane , Fatehi Salama El , Ater Mohammed , Hmimsa Younes
Published: April 2023

Moroccan chestnut populations cover a small area in northern Morocco. They occupy great environmental and socio-economic interests. Nonetheless, such interests remained unvalued and little studied. This study aims to characterize and assess phenotypic similarities (or disparities) among the Moroccan populations of C. sativa via univariate and multivariate analyses of leaves traits. The experiments involved 6200 leaves from 31 populations, 10 trees per population, and 20 leaves per tree. Six morphometric parameters [blade area (S), perimeter (P), lamina length (LL), lamina width (LW), distance between the base and largest width (DBW), petiole length (PL)] and four ratios [LL/LW, LL/LP, LL/DBW, DBW/LP] were analyzed. Analysis of descriptive statistics within and between populations showed large variations among the studied parameters. This trend was supported as well by the analysis of variance (ANOVA) which revealed a highly significant differences (P <0.0001). Furthermore, the statistical analysis revealed a high phenotypic plasticity. The correlation analysis showed a significant relationship between most of the studied parameters. The principal component analysis (PCA) assigned the studied populations into two groups. We conclude that the studied parameters have great potential to determine the phenotypic polymorphism of C. sativa populations
Evaluation of the use of alternative control methods of coffee tree diseases in the tropical Amazon
Authors: Queiroz Ruan Sobreira de , Botelho Juliana Formiga , Frozzi José Cezar , Anjos Marcelo Rodrigues dos , Vaz Marcos André Braz , Silva Ezequiel Soares da , Souza Moisés Santos de
Published: April 2023

The present study aimed to evaluate the effect of alternative products on the control of coffee brown-eye spot and coffee rust. The experiment was carried out in two conilon coffee plantations, in the following agroforestry system models: a) continuous system (SM-1) and b) mixed system (SC-2). The following treatments were used: i) aqueous plant extract of Himatanthus sucuuba (2%) - SUC, ii) Bordeaux mixture (2%) - CB and iii) control (water). Four monthly samplings of the temporal progress of the diseases were carried out, during the period from October/2019 to January/2020, evaluating the symptoms in three leaves per plant, one from each of the upper, middle and lower thirds of the plant. Incidence percentages were determined according to the number of leaves with symptoms in relation to the total number of leaves sampled. In order to estimate severity, diagrammatic scales were used for each disease evaluated. The obtained data were submitted to routine statistical analysis in R programming with a significance of 5%. Interaction effects were not significant according to the ANOVA test. Significant differences were observed among the treatments studied for the two diseases with the following results: percent reduction of rust incidence: (SUC - 50%, CB - 80% and TEST - 95%) and percent reduction of brown-eye spot: (SUC - 30%, CB - 60 % and TEST - 80%). SUC treatment was more effective in reducing disease severity with the following results: (SUC - 0.26%, CB - 0.40% and TEST - 0.83%) and (SUC - 0.35%, CB - 0.41% and TEST - 0.99%) for rust and brown-eye spot diseases, respectively. The treatment (SUC) proved to be a promising alternative product for the management of brown-eye spot and rust diseases.
Microwave drying of sweet potato: Drying kinetics and energetic analysis
Authors: Junqueira João Renato de Jesus , Corrêa Jefferson Luiz Gomes , Junior Irineu Petri , Gatti Isabella Pereira , Mendonça Kamilla Soares de
Published: April 2023

The shelf life of the sweet potato is short due to its high water activity. Therefore, preservative techniques are mandatory. In this sense, the effects of osmotic dehydration (OD) as pretreatment, two different osmotic agents (OA), sucrose and sorbitol, and microwave power density (PD) on the drying kinetics of sweet potato slices (SPS) were studied. The SPS were immersed (pretreated) or not (untreated) in an osmotic solution at aw = 0.900. The samples were placed in the microwave and the drying proceeded until the moisture content was 0.20 ± 0.02 kg water/kg. The results showed that drying time, effective diffusivity, and specific energy consumption (SEC) increased with both increasing the microwave PD and employing OD. The effective diffusivity and SEC ranged from 5.701 × 10-10 to 5.218 × 10-9 m2/s and from 7.702 MJ/kgwater to 15.608 MJ/kgwater, respectively. An adapted model was achieved for describing the drying behavior and presented suitable adjustments. According to the results, 10W/g - sucrose must be selected for drying SPS. Drying time, SEC and η at this level were 480 s, 7.702 MJ/kgwater and 29.30%, respectively
Spatial variability of the productive capacity of teak (Tectona grandis Linn F.) plantations in the eastern Amazonia
Authors: Santos Mario Lima dos , Miguel Eder Pereira , Silva José Natalino Macedo , Santos Cassio Rafael Costa dos , Lima Michael Douglas Roque , Costa Beatriz Cordeiro , Costa Luiz Rodolfo Reis , Martins Walmer Bruno Rocha , Raddatz Dione Dambrós , Rosa Rossana Cortelini da , Dionisio Luiz Fernandes Silva , Maciel Maria de Nazaré Martins , Souza Hallefy Júnio de
Published: April 2023

Application of geostatistics in mapping the productive capacity of forest stands is an important tool to guide decision making regarding precision silviculture. In this study, we investigated the productive capacity of teak clonal plantations and its spatial dependence, making the site mapping possible. We also investigated the influence of soil chemical attributes on productive potential. We used dominant height, age and geographic coordinates data from plots during five evaluations in clonal teak plantations of different ages. We performed the classification of the forest sites by the guide-curve method. The principal components analysis was used to group the forest stands according to soil chemical attributes (available P and exchangeable K, Na and Mg). The spatial variability analysis of productive capacity was carried out through geoestatistics. The results show that the productive capacity has spatial dependence. The exponential model has provided the best estimates of dominant height, revealing that 69.2% of the mapped area was from medium and 30.8% from high productive capacity. The multivariate analysis showed that soil fertility has influenced the productive capacity, discerning the most productive sites, in agreement with the soil quality. The geostatistical technique was efficient to estimate the productive capacity in unsampled areas, revealing sites with different productive potentials and their response to edaphic factors. This may assist in the efficient management of planting, when establishing silvicultural actions in specific locations, which are identified in the planted area maps, reducing the management costs.
Investigating the sustainable performance of a nanoscale zerovalent iron permeable reactive barrier for removal of nitrate, sulfide, and arsenic
Authors: Naghikhani Ali , Karbassi Abdolreza , Sarang Amin , Baghdadi Majid
Published: April 2023

The quality of groundwater resources is at catastrophic risk. The proper performance of iron nanoparticles has made a permeable reactive barrier (PRB) an alternative to conventional filtration methods. The performance of nanozerovalent iron (nZVI) PRBs is limited by particle aggregation, instability, and phase separation, even at low iron concentrations. Therefore, the precipitation of reactive materials and a decrease in the longevity of PRB are fundamental challenges. A laboratory setup is used to compare the performance of bare nZVI and xanthan gum (XG)-nZVI + Mulch PRB to simultaneously remove nitrate, sulfide, and arsenic in groundwater. nZVI (average diameter of 35–55 nm) particles are used as reactive media. The objectives are (1) to develop a method for treating nitrate, sulfide, and arsenic simultaneously in groundwater using organic mulch and XG-nZVI; and (2) to evaluate the longevity performance of the XG-nZVI + Mulch and bare nanoparticles treatment system over 10 days. The results showed that the XG-nZVI + Mulch barrier's performance for eliminating NO3-, As, and S2− was generally improved compared to the bare nZVI barriers by 5.7, 19.2, and 10.9%, respectively. Finally, despite the need for long-term sustainability assessment, XG-nZVI PRB performance is impressive, and this stability promises to improve the longevity of nanoparticles while used in PRBs.
Comparative study of the adsorptive removal of reactive yellow 14 azo dye from an aqueous solution on different synthetic materials
Authors: El Aggadi Sanaa , Ennouhi Mariem , Kerroum Younes , El Hourch Abderrahim
Published: April 2023

The purpose of this study is to investigate the adsorption behavior of the Reactive Yellow 14 (RY14) azo dye from an aqueous solution onto silica gel (SG), alumina (AO) and powdered activated carbon (PAC) via batch adsorption technique at room temperature (25 °C). Physicochemical properties of the adsorbents were characterized by means of scanning electron microscopy (SEM) coupled with energy-dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD). The factors influencing the adsorption of SG, AO and PAC, such as adsorbent dosage, pH, ionic strength, contact time and initial concentration, were conducted to evaluate the adsorption performance. The kinetic studies indicated that the adsorption of RY14 on SG and PAC can be very well fitted by a pseudo-second-order kinetic model, and onto AO by a pseudo-first-order kinetic model. The equilibrium data were best described by a Langmuir model for all adsorbents. The maximum estimated adsorption capacity was 124.6, 116.2 and 200.7 mg·g−1, for SG, AO and PAC, respectively.
Temporal moment-based approach to understand the dissolved-phase LNAPL recovery and associated characteristics in the porous system under dynamic groundwater table conditions
Authors: Guleria Abhay , Gupta Pankaj Kumar , Chakma Sumedha , Yadav Brijesh Kumar
Published: April 2023

The dissolved-phase hydrocarbon recovery can be the first step in decontaminating the soil–water system if spilled with light/dense non-aqueous phase liquid (L/D-NAPL). This study proposes a temporal moment-based approach to investigate the effectiveness of groundwater table manipulations for recovering dissolved-phase byproducts of light non-aqueous phase liquid (LNAPL) from the subsurface system. Temporal moments were computed utilizing experimentally observed and HYDRUS-simulated dissolved-phase toluene concentration data, representative of LNAPL, under stable and dynamic groundwater table fluctuation (GWTF) scenarios. Zeroth temporal moment (ZTM) showed that the hydrocarbon mass recovery varied from 1,804 to 5,190.6 mg/L × h, with the highest variation for the rapid GWTF scenario. An increase in the ZTM of hydrocarbon was observed with an increase in the rate of change of magnitude of the water table and pore velocity fluctuation as in the case of a rapid GWTF as compared to a stable GWTF case. The value of mean residence time for the stable groundwater table case was highest for the entire experimental duration, followed by slow, general, and rapid cases. Temporal moment analysis revealed that the high dissolved-phase hydrocarbon recovery could be achieved by manipulating groundwater table conditions. The present study provides a powerful technique to improve dissolved hydrocarbon remediation in mineral aquifers using hydrological restorations.
A comparison of the SCS-CN-based models for hydrological simulation of the Aghanashini River, Karnataka, India
Authors: Singh Harmandeep , Alam Mohammad Afaq , Sharma Priyank J. , Rautela Kuldeep Singh
Published: April 2023

This present study investigates different techniques for estimating the surface runoff using the Soil Conservation Service Curve Number (SCS-CN) method for the Aghanashini River in Karnataka, India. The SCS-CN method is a simplified approach for runoff estimation, but it does not take into account the actual moisture content in the soil. Consequently, insignificant moisture level changes could induce significant variations in the runoff. The study analyzes six different models based on the SCS-CN method, including the original SCS-CN model and several variations with added features (SCS-CN with slope correction, SCS-CN with λ-optimization, Mishra and Singh, Michel-Vazken -Perrin (MVP), Activation Soil Moisture Accounting SCS-CN). The accuracy of each model was compared using several goodness-of-fit statistics. Furthermore, based on the flood frequency analysis, three large flood events were reported in 2005, 2013, and 2014. The results showed that the MVP model was the best-performing method in simulating runoff. The outcomes of this study can provide valuable information to the local authorities in making informed decisions about flood forecasting and water conservation.
Domestic institutions and international collective action problems: International water rights conflicts
Authors: Yetim Müşerref
Published: April 2023

To what extent do domestic institutions affect the solution of collective action problems in international waters? Dwindling water resources and dire climate change projections make the determination of water rights in international rivers a major source of contention among states. If the states cooperate based on integrated water resource management principles, they could achieve social equity, economic efficiency, and sustainability. Yet, many international rivers remain subject to unilateral exploitation. This paper explores the role of domestic institutions in facilitating the emergence of international water rights. Adopting a political economy approach, it presents a case study analysis of the dispute over the Euphrates and explores the complex interaction of governing institutions in achieving efficient water management. I argue that the solution to the collective action dilemma in water rights is the creation of property rights institutions, which requires high levels of trust and reciprocity among highly motivated actors, who are accountable to their people.
Study of Si(100) surface step convergence kinetics
Authors: Yesin M.Yu.  , Deryabin A. S.  , Kolesnikov A. V.  , Nikiforov A.I.
Published: April 2023

In this work, the convergence kinetics investigations of the SA- and SB-steps on Si(100) substrates with inclination 0.5o and 0.1o were carried out. Analysis of the time dependence of reflection high-energy electron diffraction (RHEED) intensity was used to establish the growth kinetics character on vicinal Si(100) surfaces. It is shown that, in a Si flow at the growth rate of 0.37 ML/s, the step convergence velocity has a decreasing exponential dependence with the temperature increase. It is determined that the single-domain surface formation velocity increases with an increase in the terrace width on the surface, which may be due to the partial participation of growth due to the formation of two-dimensional islands. Above a temperature of 650oC, the dominant growth mode is due to the step movement and the single-domain surface formation velocity decreases with an increase in the terrace width. Thus, the single-layer step convergence is determined by both the MBE growth conditions and the Si(100) substrate orientation. The convergence of SA- and SB-steps of the Si(100) surface is explained by the slowdown of the step SA-motion, which is associated with complex permeability mechanisms and a kink formation of steps. It is assumed that the reason for the slowdown of the step convergence with increasing temperature is an increase in the kink density at the SA-step, which reduces the step SA-permeability coefficient. Keywords:: Molecular-beam epitaxy, reflection high-energy electron diffraction, surface, terraces, steps, kinks.
Determination of 2DEG parameters in LED heterostructures with three quantum wells In-=SUB=-x-=/SUB=-Ga-=SUB=-1-x-=/SUB=-N/GaN by terahertz time-domain spectroscopy (THz-TDs)
Authors: Burmistrov E. R.  , Avakyants L. P.
Published: April 2023

Terahertz time-domain spectroscopy (THz-TDs) has been used to record the resonant frequencies of plasmon oscillations excited in samples of heterostructures with three InxGa1-xN/GaN quantum wells (QWs) by laser pulses with a duration of 130 fs in the temperature range from 90 to 170 K. Fast Fourier transform (FFT) of the time dependence of the electric field of THz-pulses made it possible to obtain the frequency spectra of the power and phase shift of THz-radiation, the interpretation of which made it possible to estimate the pulse relaxation time, mobility and effective mass of two-dimensional electron gas (2DEG) in the heterostructures. Using a series of frequency spectra of the power and phase shift of THz-radiation, the temperature dependences of the effective mass and relaxation time of the 2DEG pulse were obtained. Mobility value 2DEG obtained by the THz-TDs is in good agreement with the data of Hall measurements. Keywords: heterostructures, pulse relaxation time, 2DEG, terahertz radiation, terahertz spectroscopy.
Non-steady-state photo-EMF in a periodically poled MgO : LiNbO-=SUB=-3-=/SUB=- crystal
Authors: Bryushinin M. A.  , Kulikov V. V.  , Sokolov I. A.  , Savchenkov E. N.  , Burimov N. I.  , Shandarov S. M.  , Akhmatkhanov A. R.  , Chuvakova M. A.  , Shur V. Ya.
Published: April 2023

The diffusion mode of the non-steady-state photo-EMF excitation is investigated in periodically poled MgO : LiNbO3 crystal at light wavelength λ=457 nm. The signal excitation is carried out along the polar axis of the crystal; the dependencies of the signal amplitude versus the phase modulation frequency, intensity and spatial frequency of the interference pattern are studied in this geometry. The analysis of these dependencies allows determining the photoelectric parameters of the material --- the type, value and relaxation time of the photoconductivity, as well as the diffusion length of charge carriers. Keywords: non-steady-state photo-EMF, periodic domain struc ture, lithium niobate.
Dispersion of dielectric permittivity and electrical modulus in Ag-=SUB=-x-=/SUB=-HfS-=SUB=-2-=/SUB=- compounds with a layered structure
Authors: Pleshchev V. G.
Published: April 2023

According to the impedance spectroscopy data, a significant frequency dispersion of the real and imaginary components of the permittivity was found in the intercalated AgxHfS2 samples. Using the modular formalism, the dielectric relaxation times were determined, which decrease in magnitude with an increase in the silver content in the samples. Their coincidence with the relaxation times determined from the frequency dependences of the imaginary parts of the complex impedance was shown. Keywords: Intercalates, impedance, hafnium disulfide, silver, dielectric permittivity, electrical module.
Photoluminescence of hafnium oxide synthesized by atomic layer deposition
Authors: Bulyansky S. V.  , Litvinova  K. I.  , Kirilenko E. P.  , Rudakov G. A.  , Dudin A. A.
Published: April 2023

In this article, we consider defect formation in hafnium oxide, which belongs tohigh-K-dielectrics and is a promising material in different areas of nano- and optoelectronics. Hafnium oxide, synthesized by the method of atomic layer deposition, usually forms with a significant oxygen deficiency and contains large number of vacancies. The oxygen vacancies characterized by photoluminescence methods. We showed that the electron-phonon interaction greatly influenced on formation of emission bands. In this case, the emission band can't identify only by the emission maximum. We need to calculate such band parameters as heat release and the energy of a purely electronic transition. This energy that can be compared with the results of theoretical calculations from the first principles. Keywords: hafnium oxide, photoluminescence, electron-phonon interaction.
Study of domain wall dynamics in GdFeCo using double high-speed photography
Authors: Prabhakara K. H.  , Shapaeva T. B.  , Yurlov V. V.  , Zvezdin K. A.  , Zvezdin A. K.  , Davies C. S.  , Tsukamoto A.  , Kirilyuk A. I.  , Rasing Th.  , Kimel A. V.
Published: April 2023

Using the technique of double high-speed photography method, we show that an external magnetic field triggers in GdFeCo domain wall motion with velocities up to 1.2 km/s. The domain wall velocity saturates with an increase of the driving magnetic field. Contrary to earlier experiments on iron garnets, we did not succeed to detect any effect of femtosecond laser pulses on the domain wall velocity, even if the pulses were strong enough to reverse magnetization. Keywords: ferrimagnetism, domain wall dynamics, high-speed photography method, Faraday effect.
Magnetic properties of NaNiFe-=SUB=-2-=/SUB=-(VO-=SUB=-4-=/SUB=-)-=SUB=-3-=/SUB=- compound at low temperatures
Authors: Drokina T. V.  , Bayukov O. A.  , Velikanov D. A.  , Freidman A. L.  , Petrakovsky G. A.
Published: April 2023

In the low temperature region, a change in the magnetic state was detected in the new NaNiFe2(VO4)3 magnetic compound, confirmed by the results of experimental study by gamma resonance and magnetometry methods. The formation of disordered magnetism in multicomponent vanadate is facilitated by the features of the crystal structure, in which magnetically active cations occupy several crystallographically non-equivalent mixed positions with uneven filling with iron and nickel ions. Keywords: multicomponent vanadates, magnetic properties, spin disorder.
Magnetic transitions and different valence states of manganese ions in solid solutions (Ni,Cu,Mn)-=SUB=-3-=/SUB=-BO-=SUB=-5-=/SUB=-
Authors: Sofronova S. N.  , Eremin E. V.  , Veligzhanin A. A.  , Chernyshov A. V.  , Kartashev A. V.  , Velikanov D. A.
Published: April 2023

The content of metal ions and their valence state for three NixCuyMn3-x-yBO5 compositions were estimated by EXAFS and XANES spectroscopy methods. In all three compositions, the copper y content did not exceed 0.25; in the third composition, some manganese ions entered the compound not only in the trivalent, but also in the divalent state. A detailed study of the magnetic properties showed that two magnetic transitions are observed in all compositions: one in the region of 60-75 K, and the second in the region of 10 K. Based on the exchange interactions calculated within the framework of the empirical model, the magnetic ordering temperatures for two- and three-lattice magnets were determined and it was assumed that the magnetic transition in the region of 60-75 K is associated with the ordering of magnetic moments in positions 2 and 3. Keywords: ludwigites, magnetic phase transition, indirect exchange interactions.
Effect of temperature on magnetoimpedance in amorphous microconducts Co-=SUB=-27.4-=/SUB=-Fe-=SUB=-5-=/SUB=-Ni-=SUB=-43.08-=/SUB=-B-=SUB=-12.26-=/SUB=-Si-=SUB=-12.26-=/SUB=-
Authors: Alam J.  , Nematov M. G.  , Yudanov N. A.  , Hashim H.  , Kurochka A. S.  , Nuriev A. V.  , Panina L. V.  , Kostishin V. G.
Published: April 2023

A study of the temperature behavior of high-frequency magnetoimpedance (MI) in amorphous microcircuits in a glass shell up to the Curie temperature TC has been carried out. Samples from the alloy Co27.4Fe5B12.26Si12.26Ni43.08 with a low Curie temperature (TC~48oC) and negative magnetostriction were used. Near TC, the impedance curves retain their characteristic behavior for materials with circular anisotropy, but the sensitivity of MI with respect to the field decreases sharply. The change in impedance with temperature becomes significant only in the presence of an external magnetic field. With an increase in temperature from room temperature to TC, the relative change in impedance can reach 140-275% in the frequency range 0.1-0.9 GHz and a magnetic field of ~10 Oe. Taking into account the location of TC in an almost important temperature region, the results obtained are interesting for the development of miniature temperature sensors, including contactless embedded sensors. Keywords: amorphous alloys, MI-effect, circular anisotropy, spin-orientation transition.
Investigation of Magnetocaloric Effect in a New Perovskite Oxide La-=SUB=-0.7-x-=/SUB=-Ho-=SUB=-x-=/SUB=-Sr-=SUB=-0.3-=/SUB=-MnO-=SUB=-3-=/SUB=- (x=0.2 and 0.3)
Authors: Pal S.  , Basu A.
Published: April 2023

The magnetocaloric effect (MCE) of La0.7-xHoxSr0.3MnO3 (x=0.2 and 0.3) perovskite oxides has been investigated. A phenomenological model is adopted for simulation of magnetization variation with temperature to investigate magnetocaloric properties such as magnetic entropy change, heat capacity change and relative cooling power. The results indicate the potential of this series of materials to achieve the MCE at temperatures near Curie temperature (TC). These compounds present as prospective candidates for cooling system in a wide temperature interval in the vicinity of room temperature. The results confirm that the phenomenological model is undoubtedly beneficial for the prediction of the magnetocaloric effect of magnetic materials. Moreover, the effect of holmium (Ho) doping in MCE of La0.7Sr0.3MnO3 has been discussed comparing the results obtained from our calculation for Ho-doped La0.7Sr0.3MnO3 and for non-doped La0.7Sr0.3MnO3 calculated earlier. Keywords: solid state magnetic refrigeration, phase transition, phenomenological model.
Ferroelectric properties of lead zirconate titanate thin films obtained by RF magnetron sputtering near the morphotropic phase boundary
Authors: Staritsyn M. V.  , Fedoseev M. L.  , Kiselev D. A.  , Kaptelov E. Yu.  , Pronin I. P.  , Senkevich S. V.  , Pronin V. P.
Published: April 2023

An experimental study of the crystal structure and ferroelectric properties of <110>-textured lead zirconate titanate films with a fine variation in their composition (with a change in the elemental ratio of zirconium and titanium atoms within 1.5%) near the morphotropic phase boundary revealed jump-like changes in the pseudocubic lattice parameter, dielectric permittivity and residual polarization. It is assumed that the observed anomalies correspond to a morphotropic transition from a rhombohedral to a mixture of tetragonal and monoclinic phases. Keywords: fine composition variation, phase state, piezoresponse force microscopy, abnormal dielectric and piezoelectric properties.
Paramagnetic centers of vanadium and iron in Na-=SUB=-5-=/SUB=-AlF-=SUB=-2-=/SUB=-(PO-=SUB=-4-=/SUB=-)-=SUB=-2-=/SUB=- single crystal
Authors: Vazhenin V. A.  , Fokin A. V.  , Potapov A. P.  , Artyomov M. Yu.
Published: April 2023

The orientation behavior of the EPR-transitions of uncontrolled V4+ (S=1/2) and Fe3+ (S=5/2) impurity centers in a Na5AlF2(PO4)2 single crystal doped with chromium has been studied. The parameters of the spin Hamiltonian of these centers are determined both in the laboratory (crystallographic) and in the local coordinate systems. Based on the fact of the existence of mixed vanadate-phosphates and taking into account the orientation of the principal axis V4+, it was concluded that vanadium replaced the position of phosphorus. The closeness of the principal axes of the fine structure tensors of the second and fourth ranks of Fe3+ centers to the F-F direction of the fluorine-oxygen octahedron surrounding the iron ion was found. Keywords: impurity ions, paramagnetic resonance, hyperfine interaction.
Evolution of Structural and Spectral Characteristics of Lu-=SUB=-0.99-x-=/SUB=-Sm-=SUB=-x-=/SUB=-Eu-=SUB=-0.01-=/SUB=-BO-=SUB=-3-=/SUB=- orthoborates
Authors: Shmurak S. Z.  , Kedrov V.V.  , Kiselev A. P.  , Fursova T. N.  , Zver'kova I. I.
Published: April 2023

The structure, IR absorption and luminescence spectra, and morphology of Lu0.99-xSmxEu0.01BO3 (0≤ x≤0.99) orthoborates synthesized at 970oC were studied. With an increase in the Sm3+ concentration, a successive change of five structural states is observed: calcite (0≤ x≤ 0.1)-> calcite + vaterite (0.1<x<0.3)-> vaterite (0.3≤ x≤ 0.95)-> vaterite + a triclinic phase (0.95 a triclinic phase (0.98<x≤1). A wide range of Sm3+, concentrations at which the vaterite phase (0.3≤ x≤ 0.95) exists and a very narrow region of triclinic phase formation (0.98<x≤1) are important distinctive features of this system. Correspondence between the structure and spectral characteristics of these compounds was established. It is shown that the vaterite phase appears in the bulk of the microcrystals of the samples that have a calcite structure. Keywords: rare earth orthoborates, crystal structure, X-ray diffraction analysis, IR-spectroscopy, luminescence spectra.
Optical properties of heterostructure CdTe/CdMgTe doped in various ways
Authors: Agekyan V.F.  , Verbin S.Yu.  , Karczewski G.  , Serov A.Yu.  , Filosofov N.G.  , Shtrom I.V.
Published: April 2023

The reflection and luminescence spectra of a CdTe/CdMgTe heterostructures doped with iodine are studied. Iodine was introduced either into a barrier layer or into a wide CdTe quantum well. It is shown how the doping method and level affect the spectra and the temperature dependence of the quantum well exciton emission intensity. Keywords: heterostructure CdTe/CdMgTe, doping, exciton, luminescence.
Ab initio simulations of dielectric and optical properties of ices I-=SUB=-h-=/SUB=-, I-=SUB=-II-=/SUB=- and lattices of hydrates sI, sH
Authors: Yunusov M. B.  , Khusnutdinoff R. M.
Published: April 2023

The results of calculating the dielectric and optical characteristics of solid polymorphic phases of water ices Ih, III and lattices of hydrates sI, sH are presented. Static dielectric tensors εik and complex frequency-dependent tensors εik(ω) are calculated for these materials. It is shown that, in terms of optical properties, the crystal lattices Ih, III, and sH are uniaxial, the tensor components εxx(ω) and εyy(ω) coincide for them, and the hydrate lattice sI is isotropic. Based on the calculated frequency-dependent dielectric functions ε'ik(ω) and ε''ik(ω), important optical characteristics were obtained: reflection R(ω), absorption a(ω), loss function L(ω), refractive indices n(ω) and k(ω). Comparison of the dielectric and optical spectra of the sI and sH gratings with the known spectra for methane hydrate sI revealed a broadening of the spectra in the high-energy direction. For the unfilled hydrate sI, a reflection peak was found at an energy of 17.3 eV, the appearance of which is associated with a change in the electronic structure of the crystal in the absence of a methane molecule. Qualitative agreement is obtained between the reflection spectra R(ω) and the functions ε'ik(ω), ε''ik(ω), calculated by quantum mechanical simulation, with experimental spectroscopy data for hexagonal and amorphous ices. Keywords: ice, hydrate, dielectric tensor, optical functions.
Molecular Dynamics Studies of the Process of Crystallization and Growth of Gas Hydrates in a Strongly Supercooled Two-Phase "Methane-Water System"
Authors: Khusnutdinoff R.M.  , Khairullina R.R.  , Yunusov M.B.
Published: April 2023

The processes of nucleation and growth of methane hydrate in a highly supercooled two-phase "methane-water" system obtained using various cooling protocols are considered. It has been shown that, at sufficiently high cooling rates, crystalline forms of methane hydrate can still form in the system. It was found that, at a cooling rate of γ=1.0 K/ps, the process of nucleation and growth of gas hydrate was observed in all independent molecular dynamics iterations, while at a cooling rate of γ=10.0 K/ps, no nucleation event was observed in ~26.7% of numerical experiments. It was found that with an increase in the cooling rate of the system, an increase in the average time scale of nucleation tauc and a decrease in the critical size of the nucleus nc are observed. It is shown that at a sufficiently deep level of supercooling of the system, the scenario of homogeneous crystalline nucleation is realized at the initial stage of the phase transition. Keywords: molecular dynamics, crystallization, methane hydrate.
Geographic Variations in Driving Distance to Mental Health Facilities, Digital Access to Telecommunication Technology, and Household Crowdedness in the United States (Preprint)
Authors: Negaro Sophia Nancy Dennett , Hantman Rachel M. , Probst Janice C. , Andrews Christina M. , Crouch Elizabeth , Hung Peiyin
Published: April 2023

BACKGROUND

Rural residents face significant barriers in accessing mental health services. As the need for these services increases and greater emphasis is put on telemedicine, examining geographic availability of mental health facilities and facilitators of telemedicine utilization is critical.

OBJECTIVE

To examine geographic variations in driving time to mental health facilities, digital access to telehealth services, and household crowdedness.

METHODS

This cross-sectional study used ZIP Code Tabulation Area (ZCTA)-level data from the 2015-2019 American Community Survey and 2021 SAMHSA Behavioral Health Treatment Services Locator to examine rural-urban differences in driving times to specialty mental health facilities, digital technology, and ZCTA-level household crowdedness.

RESULTS

Driving to outpatient facilities took longer in rural areas, with 8,545 (86.5%) of small rural ZCTAs and 3,535 (74.6%) of large rural ZCTAs being > 30 minutes from outpatient care, versus 7,655 (43.7%) of urban ZCTAs. Within those > 30 minutes, 522,154 (16.5%) rural households versus 237,800 (11.9%) urban households had no digital devices. Multivariable results show greater driving times to any mental health facility for small/isolated rural areas (8.6 minutes; 95% confidence interval CI, 8.2-9.1) than for urban areas.

CONCLUSIONS

Rural communities are farther from mental health facilities and have lower digital access than urban communities.