This study aims to: (1) Describe the level of students council administrators’ understanding of self-leadership and its application before being given the services. (2) Knowing how much the Group Guidance service influence to improve the student self-leadership in SMA N 1 Singkawang. The research used is quantitative research, with a one-group pretest-posttest design. The population in this study was all the students of council management of SMA N 1 Singkawang, they were 30 students. The study sample was taken purposively with the number of research samples of 9 students. The data collection techniques used in this study were questionnaires, interviews, and documentation, while the data collection instrument in this study used questionnaire guidelines, interview guidelines and documentation in the form of photos of activities. The data analysis technique used Quantitative Percentage Description and Wilcoxon Matched Pairs test analysis. From the results of the percentage description, the results of 3 students were obtained in the high category, 15 students were in the medium category, 8 students were in the less category and 4 students were in a low category. The data were analyzed using the SPSS.25 application. Based on the testing result, it is known that Asymp. Sig. (2-tailed) is worth 0.008. Because the value of 0.008 is smaller than 0.05 (0.008 < 0.05) it can be concluded that H1 is accepted or there is an influence of group guidance services on the self-leadership of the student council management in SMAN 1 Singkawang.

Electronic correlations play important roles in driving exotic phenomena in condensed matter physics. They determine low-energy properties through high-energy bands well-beyond optics. Great effort has been made to understand low-energy excitations such as low-energy excitons in transition metal dichalcogenides (TMDCs), however their high-energy bands and interlayer correlation remain mysteries. Herewith, by measuring temperature- and polarization-dependent complex dielectric and loss functions of bulk molybdenum disulphide from near-infrared to soft X-ray, supported with theoretical calculations, we discover unconventional soft X-ray correlated-plasmons with low-loss, and electronic transitions that reduce dimensionality and increase correlations, accompanied with significantly modified low-energy excitons. At room temperature, interlayer electronic correlations, together with the intralayer correlations in the c -axis, are surprisingly strong, yielding a three-dimensional-like system. Upon cooling, wide-range spectral-weight transfer occurs across a few tens of eV and in-plane p–d hybridizations become enhanced, revealing strong Coulomb correlations and electronic anisotropy, yielding a two-dimensional- like system. Our result shows the importance of strong electronic, interlayer and intralayer correlations in determining electronic structure and opens up applications of utilizing TMDCs on plasmonic nanolithrography.

Pengabdian ini berjudul Pelatihan Manajemen Keuangan Sebagai Kunci UKM Bisa Berkembang di Masa Pandemic COVID-19 Untuk meningkatkan kemapuan manajemen keuangan pelaku UMKM. Tujuan umum dari kegiatan pengabdian kepada masyarakat ini adalah Memberikan pelatihan dan pengetahuan secara praktis ilmu manajemen keuangan dalam rangka meningkatkan kemampuan pelaku UMKM untuk mengembangkan usaha dimasa COVID-19 dan dimasa yang akan datang. Metode yang digunakan adalah metode survey dan penyampaian materi secara langsung dan diskusi mengenai manajemen pemasaran, peraturan-peraturan yang menyangkut teknik-teknik dan penerapan manajemen keuangan yang baik. Kesimpulan dari pengabdian kepada masyakat ini adalah bahwa akan dilakukan pendampingan dalam melewati masa pandemic Covid 19 dengan memaksimalkan penerapan manajemen keuangan yang baik dalam aktifitas sehari-hari terutama bagi pelaku UKM.

A recent experimental study on SrNbO3.4 material has revealed a very pronounced anisotropy of its complex dielectric function. This material shows a metallic characteristic along a crystal direction but behaves as an insulator along b and c crystal directions. To investigate this interesting phenomenon, we perform first-principles calculations within density functional theory, to theoretically produce the complex dielectric functions along those crystal directions, and predict the anisotropy of the corresponding reflectance. This result ensures its anisotropic optical property and can explain the unique feature of this material under exposure of electromagnetic radiation.

Two-dimensional transition metal dichalcogenides, such as MoS2, exhibit several polymorphs, namely semiconducting 1H, metallic 1T, and semi-metallic 1T'. Recent experiment [Xinmao Yin et al., Nat. Commun. 8, 486 (2017)] showed an inverted gap of 0.5 eV and a fundamental gap of 0.1 eV in the absorption spectrum of the semi-metallic 1T'-MoS2. We carry out first-principles calculations on the electronic band structure of 1T'-MoS2. Since the transition across the fundamental gap occurs at a non-high-symmetry k-point, the choice of k-point sampling is crucial. Our converging result regarding k-point sampling shows that two bands touch at Fermi energy. It indicates the absence of fundamental gap. We report that spin-orbit interaction induces an opening of this fundamental gap of about 0.06 eV, which is smaller than the gap observed in experiment. To see the effects of electron-electron interaction on this fundamental gap, we calculate the quasiparticle electronic band structure within the GW approximation.

Bi2Se3 has recently become the focus of research development due to its unique transport properties. It is a narrow band gap semiconductor with conducting states on its surface. A reliable and accurate calculation of the optical spectra including excitonic effects is very limited for this material. One of the reasons is that such calculations are computationally demanding since they require a very dense k-point sampling of the Brillouin zone. In this work, we use density functional theory as implemented in Quantum Espresso package to calculate the ground state properties of this material. Optical spectra are calculated within many-body perturbation theory by solving the Bethe-Salpeter equation in Yambo code to account for electron-hole interaction. A double-grid method implemented in Yambo helps us to do accurate calculations of the optical spectra with inexpensive computational cost. Furthermore, we expect that in bulk semiconductor with a narrow gap, electron-electron interaction is weak due to environmental screening. For this reason, to reduce the computational efforts, in this work we neglect the electron-electron interaction.

Transition metal dichalcogenides (TMDs) display unique properties in their monolayer structures, namely a direct band-gap transition, which becomes a promising candidate for optoelectronics applications. Among them, WS2 exhibits strong spin-orbit interaction which splits the excitonic peaks as observed in the experimental data up to ~400 meV. Unlike the other TMDs, the first excitonic peak A is very sharp for WS2, while the secondary peak B is broader with smaller relative intensity. In this paper, we perform first-principles calculations on the electronic band structure and solve the Bethe-Salpeter equation for the complex dielectric function of monolayer WS2 to study the effects of spin-orbit coupling on its excitonic structures. To resolve the excitonic peaks, in particular the B peak, we implement the double-grid method. We discuss the effects of electron-hole interaction on the absorption spectrum by comparing it with that calculated at the independent-particle level.

Graphene has been a hot subject of research in the last decade as it holds a promise for various applications. One interesting issue is whether or not graphene should be classified into a strongly or weakly correlated system, as the optical properties may change upon several factors, such as the substrate, voltage bias, adatoms, etc. As the Coulomb repulsive interactions among electrons can generate the correlation effects that may modify the single-particle spectra (density of states) and the two-particle spectra (optical conductivity) of graphene, we aim to explore such interactions in this study. The understanding of such correlation effects is important because eventually they play an important role in inducing the effective attractive interactions between electrons and holes that bind them into excitons. We do this study theoretically by developing a GW method implemented on the basis of the tight-binding (TB) model Hamiltonian. Unlike the well-known GW method developed within density functional theory (DFT) framework, our TB-based GW implementation may serve as an alternative technique suitable for systems which Hamiltonian is to be constructed through a tight-binding based or similar models. This study includes theoretical formulation of the Green's function G, the renormalized interaction function W from random phase approximation (RPA), and the corresponding self energy derived from Feynman diagrams, as well as the development of the algorithm to compute those quantities. As an evaluation of the method, we perform calculations of the density of states and the optical conductivity of graphene, and analyze the results.

Researchon thepreparation of ceria based materialfor electrolyteof solid oxide fuelcellhasbeen conducted. The Sm0.2Ce0.8O1.9(SDC) was prepared by sol-gel method and the layered composites of SDC with Y0.08Zr0.92O3-δwerepreparedbyscreenprintingmethod.This research aims to studythecrystal structure and its conductivitycharacter. XRDmeasurementequippedwithLeBailrefinementshowsthatSDCiscrystallizedin cubic structure with space group of Fm3m.Theaddition ofYSZ into SDC does not changeitscrystal structure. However, the cell parameter of SDC is reduced from 5.434036(2) Å to 5.433(0) Å. At 600 °C, SDC has electronic conductivity that indicates the presence of electrons migration that can promotes short circuit during fuel cell operation. The combination of SDC with YSZ forming a layered composite of SDC-YSZ-SDC could reduce the electronicconductivity,eventhoughitsionicconductivityisalsobecomelowerthansingleSDCatthe same temperature.

Tujuan dari penelitian ini adalah membuat biobriket dari bahan bottom ash limbah Pembangkit Listrik Tenaga Uap (PLTU) dengan biomassa cangkang kopi dengan zat pengikat tetes tebu serta menguji nilai kalor yang dihasilkan. Metode yang digunakan dalam penelitian ini adalah; pembuatan biobriket dengan memvariasi komposisi antara bottom ash dengan biomassanya serta zat pengikat yang berbeda. Variasi komposisi antara biomassa cangkang kopi dengan bootom ash yang digunakan adalah 60% : 40% dan 70% : 30%, sedangkan bahan perekatnya menggunakan tetes tebu dan tepung kanji. Pengujian yang dilakukan adalah menguji nilai kalor dari biobriket yang dihasilkan menggunakan alat uji calloriboom. Dari hasil pengujian didapatkan biobriket dengan komposisi 70% biomassa cangkang kopi dan 30% bottom ash dengan pengikat tetes tebu mempunyai nilai kalor yang paling tinggi dibandingkan dengan komposisi dan pengikat yang lain dengan nilai kalor yang dihasilkan yaitu 2496,18 kal/gr. Nilai kalor ini dipengaruhi oleh kandungan karbon aktif yang terdapat pada arang cangkang kopi dan besar kecilnya kandungan carbon, oxygen dan ash yang dimiliki, semakin tinggi kandungan carbon dan oxygen maka makin tinggi pula nilai kalor yang kandungan kalor yang terdapat pada jenis perekat tetes tebu lebih tinggi dari pada tepung kanji. [Title: Comparison of Calorific Value of Biobriket Made of Bottom Ash Waste and Biomass Plant Shell Coffee by Varying Composition and Types of Binder] This study is aimed to make biobriket of bottom ash material waste biomass power plant and different binder of coffee shell (molasses) as well as measuring the calorific value. The method in this study are by manufacturing biobricket by varying the composition of bottom ash with biomass and different binder. Biomass composition variation of the shell coffee and bottom ash are 60%:40% and 70%:30%. The binder used are molasses and starch. This experiment was carry out by measuring the calorific value of produced biobricket. From results, the biobricket with a composition of 70% biomass and 30% coffee shell bottom ash and molasses binder has the highest calorific value in comparison to other binder composition. The calorific value is 2496.18 cal/g. This calorific value is influenced by the content of activated carbon contained in charcoal shell of coffee and size of the content of carbon, oxygen and ash. Increased calorific values between the molasses and starch binders suggested that the calorific value of product when using molasses binder is higher than that of starch.