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"Beberapa studi eksperimental dan teoretis baru-baru ini mengungkapkan bahwa material dua dimensi (2D) merupakan kandidat yang menjanjikan untuk teknologi informasi berbasis seleksi derajat kebebasan elektron, spin, hingga valley, bergantung pada interaksinya dengan cahaya. Dalam hal ini, ada banyak material 2D yang perlu ditelusuri sifat elektronik dan sifat optiknya untuk mendapatkan polarisasi sifat fisis tertentu, terutama polarisasi valley yang terkait dengan seleksi derajat kebebasan keadaan elektron pada titik tertentu di ruang momentum. Melalui perhitungan first principles untuk monolayer α-Sb dan NbS2, kami memverifikasi kondisi material 2D yang dapat memiliki potensi untuk aplikasi valleytronics melalui polarisasi optik dari valley-nya. Penyerapan cahaya terpolarisasi melingkar oleh material dihitung melalui pendekatan dipol dengan menggunakan vektor dipol dan matriks elemen transisi optik. Kami menemukan bahwa elektron di valley yang berbeda pada zona Brillouin yang memenuhi simetri pembalikan waktu untuk monolayer α-Sb dan NbS2 dapat tereksitasi secara selektif oleh cahaya terpolarisasi melingkar kiri atau kanan. Khusus NbS2, intensitas maksimum polarisasi valley mencapai 100% di valley K atau K’ tergantung polarisasi cahaya melingkar (kanan atau kiri) yang diberikan. Selektivitas yang sangat baik ini diduga terkait erat dengan struktur kristal heksagon tertekuk (buckled) dengan ikatan polar yang dimiliki oleh NbS2 alih-alih struktur berkerut (puckered) dengan ikatan nonpolar dari α-Sb.

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Recent experimental and theoretical studies revealed that two-dimensional (2D) materials are a promising candidate for information technology based on selectivity of electron, spin, and valley degrees of freedom under interaction with light. In this case, there are a lot of 2D materials whose electronic and optical properties need to be investigated so that we can obtain polarization of certain physical properties, especially valley polarization which is related to the selection rule of electronic excitation by light at a certain point (the so-called valley) in momentum space. By using first-principles calculations for monolayer α-Sb and NbS2, we verify some conditions for 2D materials that are potential for valleytronics applications utilizing the optical valley polarization. In this case, we need to calculate the absorption of circularly polarized light by the materials through the dipole approximation which gives the dipole vectors and optical transition matrix elements as the main quantities to be investigated. We found that electrons at the different valleys, which satisfy time-reversal symmetry, in the Brillouin zone of monolayer α-Sb and NbS2, can be selectively excited by left-handed or right-handed circularly polarized light. Specifically for NbS2, the maximum intensity of valley polarization can reach 100\% at the K or K’ valley depending on the given (left-handed or right-handed) circular polarization of light. We expect that such an excellent selectivity in NbS2 is closely related to its buckled hexagonal lattice and polar bonding, in contrast to the puckered lattice and nonpolar bonding in α-Sb. "

"The dual-inverter fed open-end winding configuration can be categorized as a new breed of multi-level converters. The structure is simple and offers a lot of advantages. However, the development of suitable PWM schemes is more complicated, due to the availability of a large number of switching states and existence of the multiple two-dimensional planes. An overview of attempts to develop suitable modulation techniques for the dual-inverter fed five-phase machine drives recognizes that progress has been made over the past few years. This paper presents a performance comparison of three PWM schemes of the dual-inverter fed five-phase, open-end winding motor drives. The quality of the phase output voltages are compared and the adequate analyses are provided. The simulation results show that the Carrier Based Phase Disposition (PD) PWM scheme enables generation of the most excellent output voltage among the three PWM schemes. The Total Harmonics Distortion (THD) of the output voltages generated by the carrier based PWM scheme reduces by 65% and 15% on average compared to the THD of the output voltages produced by the URS PWM scheme and the decomposition PWM scheme respectively."

"ABSTRAKPada penelitian ini akan dilihat pengaruh pemanasan terak timah pada 800℃ yang disertai pendinginan cepat terhadap ukuran butir terak timah, serta variasi waktu pelindian terhadap kadar tantalum dan niobium serta pengotor – pengotornya. Pengujian XRF digunakan untuk melihat perubahan pada terak timah setelah diberi perlakuan pemanasan, pelindian basa dengan NaOH dan pelindian asam dengan HCl. Berdasarkan hasil penelitian didapat bahwa ukuran butir terak timah mengalami reduksi setelah dilakukan pemanasan yang disertai pendinginan cepat. Proses pemanasan, lalu pelindian basa yang diikuti pelindian asam mengakibatkan peningkatan kandungan tantalum dan niobium masing - masing sebesar 374% menjadi 1,564% dan 72% menjadi 1,1%.Waktu optimum untuk pelindian basa adalah 20 menit dan pelindian asam 50 menit.

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ABSTRACTn this research, the heating effect of tin slag at 800℃ followed by rapid cooling and time variation of leaching process to value of tantalum, niobium and its impurities will be observed. XRF test was used to determine the change of tin slag after heating, base leaching and acid leaching process. According to the result, the grain size of tin slag are reduced after the heating process followed by rapid cooling. Heating-rapid cooling process, base leaching and acid leaching have effect on increasing the value of tantalum and niobium in the residue with an enrichment of 374% and 72% respectively. The optimum time of leaching process is 20 minutes for base leaching and 50 minutes for acid leaching."

"Transesophageal echocardiography (TEE) is a valuable diagnostic modality now routinely used during cardiac surgery and in the intensive care unit. Increasingly, anesthesiologists trained in TEE provide the service in both settings where they face the challenge of integrating numerous current TEE guidelines into day-to-day practice. Perioperative two-dimensional transesophageal echocardiography : a practical handbook has been designed to be a concise, portable guide for using TEE to recognize cardiac pathology during the perioperative period. This compact guide has a diverse appeal for anesthesiologists, cardiac surgeons, and cardiologists desiring comprehensive up-to-date echocardiographic information at their fingertips.Features :- More than 450 full-color, high quality clinical images and illustrations- Synopsis of cardiac pathology commonly encountered in cardiac surgery patients- Convenient spiral binding- On-the-spot reference for echocardiographers with a wide range of experience, from novice to expert"

"Manifestasi klinis demam berdarah Dengue (DBD) adalah kebocoran plasma dan trombositopenia. Salah satu teori penyebab kedua hal tersebut adalah kadar trombin yang meningkat akibat aktivasi koagulasi. Kadar trombin dapat diwakili oleh kadar F1.2. Tujuan penelitian ini adalah untuk mengetahui hubungan antara kadar F1.2 dengan kebocoran plasma dan trombositopenia pada infeksi Dengue. Desain penelitian ini adalah potong lintang, mengggunakan plasma EDTA dari pasien terinfeksi virus Dengue. Subyek penelitian adalah 10 subyek dengan kebocoran plasma dan 10 subyek tanpa kebocoran plasma pada infeksi Dengue, 6 sampel berpasangan untuk perbandingan fase kritis dan fase konvalesen, 26 sampel untuk uji korelasi antara kadar F1.2 dengan jumlah trombosit.Hasil penelitian menunjukkan kadar F1.2 pada pasien terinfeksi virus Dengue dengan kebocoran plasma (rerata ± 2SD) 147,4 ± 105,82 pg/mL lebih tinggi secara bermakna dibanding tanpa kebocoran plasma 51,3 ±39,92 pg/mL. Kadar F1.2 pada fase kritis dengan median 186,3 (108,6-223,2) pg/mL lebih tinggi secara bermakna dibanding fase konvalesen 46,5(27,4-51,9) pg/mL. Terdapat korelasi negatif yang bermakna dengan kekuatan sedang antara kadar F1.2 dengan jumlah trombosit, nilai r = - 0,609. Dari hasil penelitian disimpulkan bahwa terdapat peningkatan aktivasi koagulasi yang ditunjukkan dengan peningkatan kadar F1.2 pada fase kritis, berkaitan dengan kebocoran plasma dan trombositopenia pada pasien terinfeksi virus Dengue.

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Clinical manifestations of Dengue haemorrhagic fever are plasma leakage and thrombocypenia. Both manifestations are thought to be caused by an increased thrombin level due to activation of coagulation. The aim of this study was to look for any association between F1.2 level and plasma leakage and also between F1.2 level and thrombocytopenia in Dengue infected patients. The study design was cross sectional. This study used EDTA plasma from patients infected with Dengue virus. The thrombin level was represented by the prothrombin fragment 1.2 (F1.2) level. Twenty subjects were enrolled in this study, consisted of 10 subjects with plasma leakage and 10 without plasma leakage, 6 pair samples in critical phase and convalescent phase, 26 samples for correlation test between F1.2 level and platelet count. In this study, it was found that the F1.2 level in patients with plasma leakage (mean ± 2 SD) 147.4 ± 105.82 pg/mL was significantly higher compared to patients without plasma leakage 51.3 ±39.92 pg/mL, and the F1.2 level in critical phase had a median of 186.3 (108.6-223.2) pg/mL which was significantly higher compared to convalescent phase 46.5(27.4-51.9) pg/mL. Also there was a significant negative correlation with moderate degree of relationship between F1.2 level and the thrombocyte count, r = - 0.609.

The results of the study demonstrated that there was increased coagulation activation at critical phase in patients infected with Dengue virus, as shown by F1.2 as indicator, associated with plasma leakage and thrombocytopenia."

"Rancangan sistem mekanik penggerak detektor dua dimensi untuk fantom air telah dibuat dengan menggunakan mikrokontroler H8/3069F. Sistem ini dilengkapi dengan dua buah servo motor continuous yang digunakan untuk memutar poros ulir pada sumbu vertikal dan horizontal sehingga detektor holder dapat bergerak dua dimensi sejauh 30 cm. Arah gerak servo motor continuous diatur dengan menggunakan metode Pulse Width Modulation (PWM) melalui Bahasa C yang bekerja pada mikrokontroler. Posisi aktual dari detektor dapat diketahui melalui sensor rotary encoder yang dipasang satu sumbu dengan motor. Pengaturan posisi detektor secara manual dapat dilakukan melalui PC dengan memanfaatkan tampilan Graphical User Interface (GUI) Python. RS-232 dugunakan untuk komunikasi antara komputer dan mikrokontroler. Ketelitian dari alat ini adalah 0.67% untuk sumbu vertikal dan 0.33% untuk sumbu horizontal.

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Mechanical drive system design of two-dimensional detector for water phantom had been done by using microcontroller H8/3069F. This system is equipped with two continuous servo motors in order to rotate the threaded shaft on vertical and horizontal axis so that the detector holder can move two dimensionally as far as 30 cm. The direction of continuous servo motor is set by using Pulse Width Modulation (PWM) method through C Language that works on the microcontroller.

The actual position of detector can be determined by rotary encoder sensor which is assembled in one shaft with motor. Setting the position of the detector can be automatically done through a PC by using the display Graphical User Interface (GUI) in Python. RS-232 is used for communication between computer and microcontroller. The accuracy of this device is 0.67% for vertical axis and 0.33% for horizontal axis."

"Discrete optical cavities adalah sebuah studi mengenai sistem benda optik identik yang dijajarkan dalam suatu larik periodik dengan jarak yang sama lalu ditembak oleh suatu sumber cahaya sehingga cahaya berosilasi di dalam benda optik dan memenuhi sistem persamaan nonlinear. Penempatan optik dipandang layaknya sebuah garis, figur satu dimensi. Solusi sistem persamaan nonlinear berupa soliton seperti penjelasan Yulin dan Champneys dalam paper mereka pada tahun 2010. Metode yang digunakan untuk menyelesaikan sistem persamaan nonlinear ini adalah metode Pseudo-Archlength Continuation. Discrete optical cavities dapat dikembangkan sedemikian sehingga membentuk figur dua dimensi. Sistem persamaan nonlinear dimodifikasi sedemikian sehingga berlaku bagi discrete optical cavities dua dimensi.

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Discrete optical cavities is a study about identic optical objects that arranged in a periodic array with same distance between them and it shots by a light source so that the light oscillates inside the optical objects and suffices nonlinear systems of equation. The placement of the optical objects considered as a line, in one-dimensional figure. Solution of nonlinear system of equations is soliton as described by Yulin and Champney at their paper in 2010. Method used to solve the nonlinear systems of equation is Pseudo-Arclength Continuation. Discrete optical cavities can be developed into two-dimensional figure. The nonlinear system of equations is modified so that it suffices two-dimensional system of discrete optical cavities problem."

"Pengawasan distribusi bahan radioaktif atau radionuklida merupakan hal yang penting. Hal ini mengingat bagaimana serangan dan terorisme berbasis radioaktif merupakan ancaman yang nyata. Untuk itu, diperlukan suatu algoritma yang dapat digunakan untuk mendeteksi keberadaan dan jenis dari radionuklida. Algoritma identifikasi radioaktif atau RIID (Radioisotope Identification) telah disusun secara klasik menggunakan metode seperti peak-matching atau ROI (Region of Interest). Akan tetapi, performa dari algoritma tersebut sudah didahului dengan munculnya machine learning. Salah satu subdisiplin dari machine learning, yakni deep learning, melahirkan apa yang dinamakan dengan CNN atau Convolutional Neural Network. Jenis algoritma machine learning ini sudah jamak digunakan untuk permasalahan identifikasi dan pengenalan obyek. Di dalam kerangka RIID sendiri, studi yang membahas mengenai penggunaan CNN sebagai algoritma identifikasi radionuklida sudah tidak dapat dihitung menggunakan jari. Teknik baru seperti transformasi spektrum gamma dari radionuklida menjadi data 2-D seperti suatu citra mulai diperkenalkan beberapa tahun terakhir. Penelitian ini menggabungkan teknik tersebut dengan proses colormapping, yakni ‘pewarnaan’ dari data skalar yang bergantung pada nilai data tersebut. Melalui penggabungan teknik tersebut, model CNN yang disusun pada penelitian ini mampu untuk melakukan identifikasi multikelas radionuklida dengan akurasi di atas 95%.

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Monitoring the distribution of radioactive materials or radionuclides is important. This is because radioactive attacks and terrorism are a real threat. To solve this problem, it is imperative to build an algorithm that can be used to detect and identify the presence of radionuclides. Radionuclide identification or (RIID) algorithm has been made classically using methods such as peak-matching or ROI (Region of Interest). However, the performance of these algorithms has been superseded by the emergence of machine learning. One of the sub-disciplines of machine learning, that is deep learning, has given birth to what is called CNN or Convolutional Neural Network. This machine learning algorithm has been used far and wide to solve object detection and identification problems. Within the RIID framework itself, studies discussing the use of CNN as a radionuclide are already plentiful. New techniques such as transforming the gamma spectrum of radionuclides into 2-D data have been introduced in recent years. This study attempts to combine this technique with color mapping, which is the pseudo-coloring of scalar data which depends on the value of the data. Through this combined technique, CNN models that are devised in this study can perform multiclass radionuclide identification with an accuracy higher than 95%."

"Korosi kerap menjadi masalah dalam pemipaan untuk industri minyak dan gas bumi. Untuk mengatasi masalah tersebut diciptakanlah material yang dapat menahan laju korosi, salah satunya adalah baja tahan karat duplex. Namun, baja tahan karat duplex masih rentan terkena korosi lokal di lingkungan yang terdapat ion klorida. Selain itu, pipa-pipa yang digunakan untuk mengalirkan produk industri minyak dan gas bumi dirangkai menggunakan metode las yang dapat merubah konten ferit yang dapat mempengaruhi ketahanan pipa terhadap korosi. Penelitian ini dilakukan untuk mempelajari pengaruh konsentrasi NaCl dan pengaruh perubahan konten ferit terhadap korosi duplex 2205 menggunakan metode polarisasi siklik. Hasil penelitian menunjukkan bahwa baik konsentrasi NaCl dan perubahan konten ferit memberi pengaruh pada korosi duplex 2205. Konsentrasi NaCl yang memiliki korosi paling besar adalah konsentrasi 3,5% NaCl. Peningkatan fasa austenit pada baja akan memperkuat ketahanan korosi dari baja tahan karat duplex.

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Corrosion become the problem in pipeline for oil and gas industry. To handle this problem, materials that stainless was made, one of them is duplex stainless steel. However, duplex stainless steel can be corroded by localized corrosion in environment that contain chloride ion. More over, pipes which used to stream the product of oil and gas industry is joint by welding which can affect the ferric content that can change the pipe?s resistance of corrosion.

This study was conducted to study the effect of NaCl concentration and the effect of change of ferrite content to corrosion of duplex 2205. This study shows that both of NaCl concentration and change of ferrite content have affect the corrosion of duplex 22015. 3.5% NaCl is the most corrosive environment. The increase of austenite phase will increase the corrosion resistance of duplex stainless steel."

"Lingkungan tanah perkotaan cenderung bersifat korosif terhadap logam karena faktor-faktor seperti pH, kelembapan, kandungan ion agresif, dan aktivitas manusia. Penelitian ini bertujuan untuk menganalisis mekanisme dan ketahanan korosi pada baja karbon Q235 dan Baja Tahan Karat 304 yang direndam selama 21 hari dalam tanah halaman Departemen Teknik Metalurgi dan Material Kampus UI Depok. Pengujian menggunakan metode polarisasi linear menunjukkan bahwa baja karbon Q235 memiliki nilai potensial korosi (Ecorr) yang fluktuatif, dengan puncak korosi pada hari ke-14 (Ecorr -725,485 mV vs Cu-CuSO4 dan icorr 1,14 µA/cm²). Sebaliknya, Baja Tahan Karat 304 menunjukkan peningkatan Ecorr dari -204,78 mV vs Cu-CuSO4 menjadi -72,483 mV vs Cu-CuSO4, sementara nilai icorr stabil pada 0,01 µA/cm² berkat lapisan oksida kromium. Hasil pengujian Electrochemical Impedance Spectroscopy (EIS) menunjukkan Baja Tahan Karat 304 memiliki resistansi polarisasi (Rp) tertinggi (3283200 Ω), diikuti baja karbon dengan pelapisan epoksi 200 µm (1429400 Ω) dan baja karbon tanpa pelapisan (8577 Ω). Pelapisan epoksi pada baja karbon Q235 terbukti meningkatkan ketahanan korosi secara signifikan. Baja Tahan Karat 304 adalah pilihan terbaik untuk lingkungan korosif, sementara pelapisan epoksi pada baja karbon Q235 menjadi alternatif ekonomis untuk meningkatkan ketahanan korosi. Penelitian lanjutan diperlukan untuk mengevaluasi ketahanan jangka panjang pada berbagai kondisi tanah.

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Urban soil environments tend to be corrosive to metals due to factors such as pH, moisture, aggressive ion content, and human activities. This study aims to analyze the corrosion mechanism and resistance of Q235 carbon steel and 304 stainless steel immersed for 21 days in soil at the Department of Metallurgical and Materials Engineering, Universitas Indonesia, Depok Campus. Tests using the linear polarization method revealed that Q235 carbon steel exhibited fluctuating corrosion potential (Ecorr), with peak corrosion observed on day 14 (Ecorr -725.485 mV vs Cu-CuSO4 and icorr 1.14 µA/cm²). In contrast, 304 stainless steel showed a gradual increase in Ecorr from -204.78 mV vs Cu-CuSO4 to -72.483 mV vs Cu-CuSO4, while icorr remained stable at 0.01 µA/cm² due to the protective chromium oxide layer. Electrochemical Impedance Spectroscopy (EIS) results indicated that 304 stainless steel had the highest polarization resistance (Rp) of 3,283,200 Ω, followed by epoxy-coated Q235 carbon steel (1,429,400 Ω) and uncoated Q235 carbon steel (8,577 Ω). Epoxy coating with a thickness of 200 µm on Q235 carbon steel significantly improved its corrosion resistance. In conclusion, 304 stainless steel is the best choice for corrosive environments, while epoxy-coated Q235 carbon steel provides an economical alternative for enhancing corrosion resistance. Further studies are needed to evaluate long-term resistance under various soil conditions.

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