Hasil Pencarian  ::  Simpan CSV :: Kembali

"ABSTRAKSifat transportasi elektron dalam molekul DNA Aperiodik dan Molekul DNA G4 telah dipelajari. Kedua molekul DNA ini, dimodelkan dengan menggunakan Hamiltonian ikatan kuat tight binding . Sifat transpor elektron dipelajari dengan menghitung probabilitas transmisi elektron menggunakan metode transfer matriks dan hamburan matriks secara bersamaan. Formalisme Landauer-B ttiker digunakan dalam menghitung karakteristik I-V molekul dari probabilitas transmisi. Pada molekul DNA Aperiodik dan DNA G4 sudah dilakukan perhitunganan untuk DNA berukuran 32 pasangan basa. Parameter perhitungan yang diperhatikan adalah gerakan sudut putar pasangan basa yang berhubungan dengan konstanta loncatan elektron antar basa melalui teori semi-empiris Slater-Koster-Harrison. Hasil perhitungan dianalisis dengan memperhatikan variasi frekuensi getar gerak memutar, temperatur, dan energi gangguan backbone. Hasil perhitungan pada molekul DNA Aperiodik dan DNA G4 menunjukkan bahwa transpor muatan DNA bergantung pada frekuensi gerak memutar pasangan antarbasa. Jika frekuensi tinggi, terjadi peningkatan arus dan probabilitas transmisi. Dan ketika temperatur ditingkatkan, probabilitas transmisi dan arus menurun dan tegangan ambang meningkat di tiap variasi frekuensi getar gerak memutar. Terakhir, jika nilai energi gangguan backbone yang diberikan semakin besar maka nilai transmisi, arus dan tegangan ambang menurun. Pada molekul DNA G4 transmisi dan kurva I-V lebih tinggi dari molekul DNA Aperiodik.

---

ABSTRACTElectron transport characteristics in G4 and Aperiodic DNA molecules have been studied. Both molecules are modelled using tight binding Hamiltonian. Electron transport characteristics are studied by calculating electron transmission probability using matrix transfer and scattering matrix methode simultaneously. Landauer B ttiker formalism is used in calculating the I V characteristics of molecules from transmission probability. The calculation in Aperiodic and G4 DNA molecules is done for 32 base pairs long DNA. Variable in the calculation is twisting motion angle of base pairs which is correlated to electron the hopping constant between bases within Slater Koster Harrison semi empirical theory. Calculation results are analyzed in variation of twisting motion frequency, temperature, and backbone disturbance energy. The calculation result in Aperiodic and G4 DNA molecules shows that DNA change transport on DNA depends on twisting motion frequency of bases. When the frequency become higher, the current and transmission probability will increase. Moreover, when the temperature increases, the current and transmission probability decreases, then threshold the voltage becomes higher for all twisting motion frequency. Lastly, as the backbone disturbance energy become large, the current and transmission decreases, then the threshold voltage will be small. In G4 DNA molecule the transmission and curve I V are higher, than in Aperiodic DNA molecule. "

"ABSTRAKSifat transportasi elektron di molekul DNA poly dA -poly dT telah dipelajari. Kami menggunakan dua model DNA yang berbeda, yang direpresentasikan secara matematis dengan model ikatan kuat Hamiltonian dan teori Slater-Koster. Panjang molekul DNA yang digunakan 32 pasangan basa. Kedua ujung rantai molekul dikoneksikan dengan elektroda. Sifat transportasi elektron dipelajari dari probabilitas transmisi dan karakteristik I-V. Probabilitas transmisi dihitung dengan metode transfer matriks dan matriks hamburan. Formula Landauer Buttiker digunakan untuk menghitung karakteristik I-V. Selanjutnya, sifat transportasi elektron dibandingkan di variasi temperatur, frekuensi getar gerak memutar dan energi gangguan lingkungan luar. Hasilnya menunjukan bahwa pada kedua model mengalami peningkatan probabilitas transmisi elektron dan arus seiring meningkatnya frekuensi getar gerak memutar rantai DNA. Namun saat temperatur ditingkatkan, probabilitas transmisi dan arusnya menurun dan tegangan ambang membesar di tiap variasi frekuensi getar. Kemudian ketika energi gangguan luar meningkat, probabilitas transmisi dan arus semakin kecil, demikian pula tegangan ambangnya. Nilai puncak-puncak probabilitas transmisi di model B lebih besar dari model A, namun kurva I-V model B dapat lebih besar atau lebih kecil. Peningkatan maupun penurunan transmisi dan arus di model A lebih besar ketika tidak ada gangguan backbone, tendensi terbalik ketika terdapat energi gangguan backbone.

---

ABSTRACTThe properties of electron transport in poly dA poly dT DNA molecules have been studied. We use two models of DNA which are represented mathematically by tight binding Hamiltonian model and Slater Koster theory. DNA molecules which are used have 32 base pairs long. Each end of DNA chain are connected to metallic electrodes. The properties of electron, are studied from transmission probability and I V characteristic curves. The transmission probabilities are calculated using transfer matrix and scattering matrix methods. The Landauer Buttiker formula is used in computing I V characteristics. The properties of transport electron are compared in variation of temperatures, frequencies of twisting motion and disorder energy due to environment. The results show that the transmission probability and current values increase as frequency of twisting motion increases in both of models. However, as temperature become higher, the transmission probability and current values decrease, but the treshold voltages increase for all frequency variations. Then, as disorder energy becomes higher, the transmission probability and current values decrease, and the threshold voltages decrease, too. Transmission probability values of model B are higher than model A, but the I V curve of model B can be higher and lower. Both of the enhancement or reduction of transmission and current in model A is higher for without backbone disorder energy condition, but the tendency reversed when in backbone disorder energy condition."

"Pendekatan Hamiltonian tight binding digunakan untuk mempelajari sifat transport muatan di molekul DNA. Sifat transport muatan ini dipelajari dengan menggunakan dua model DNA yaitu model DNA Aperiodik dan model DNA G4. Model DNA Aperiodik terdiri dari 32 pasangan basa ATGC yang tersusun secara acak dengan sequence GCTAGTACGTGACGTAGCTAGGATATGCCTGA. Pada model ini dilakukan perhitungan menggunakan metode transfer matriks dan metode hamburan untuk mendapatkan probabilitas transmisi serta menghitung karakteristik I-V berdasarkan formula Landauer Büttiker dengan memvariasikan nilai kopling 𝛼 interstrand. Peningkatan nilai kopling 𝛼 interstrand memberikan dampak yang sangat baik terhadap transport muatan yaitu terjadinya peningkatan probabilitas transmisi dan karakteristik IV pada tegangan tinggi. Sedangkan, model DNA G4 terdiri dari 4 basa guanine yang tersusun membentuk struktur planar, g-quartet yang disusun secara bertumpuk. Pada model DNA ini dilakukan perhitungan panjang lokalisasi menggunakan metode transfer matriks dan perhitungan density of state (DOS) dan karakteristik I-V menggunakan pendekatan fungsi green di bawah pengaruh temperatur dan medan magnet. Temperatur menyebabkan terjadinya fluktuasi termal yang menurunkan panjang lokalisasi, density of state (DOS) dan karakteristik I-V di molekul DNA G4. Sedangkan, medan magnet menyebabkan terjadinya pergeseran fase keadaan elektron di jalur transport yang mempengaruhi panjang lokalisasi dan DOS yang berimbas pada peningkatan arus hingga di tegangan tinggi.

---

The tight binding Hamiltonian approach is used in studying charge transport properties DNA molecules. The charge transport properties are studied by using two DNA models, the Aperiodic DNA molecule and the G4 DNA molecule. The Aperiodic DNA model consist of 32 base pairs that ATGC arranged randomly with sequence GCTAGTACGTGACGT-AGCTAGGATATGCCTGA. In this model, transfer matrix method and scattering method are used in obtain transmission probability and calculating the I-V characteristic for various values of interstrand coupling α. The increase of α gives a very good impact on charge transport that is the increase of transmission probability and I-V characteristic at high voltages. G4 DNA model consists of planar structure of four guanine bases, g-quartet, which are stacked on top each other. In this DNA model, localization length is calculated using transfer matrix method and the density of state (DOS) as well as I-V characteristic are calculated using green function approach under the influence of temperature and magnetic field. The temperature causes thermal fluctuations that decreases the localization length, density of state (DOS) and I-V characteristics in G4 DNA molecule. Meanwhile, magnetic field causes a shift in electron wave phase along its travel path which is affecting the localization length and DOS which lead to current increament up to high voltage."

"ABSTRAKKami mempelajari sifat transport muatan menggunakan molekul DNA aperiodik dan molekul DNA G4. Molekul DNA aperiodik mempelajari pengaruh nilai loncatan inter-strand pada karakteristik I-V. Molekul DNA G4 mempelajari pengaruh medan listrik dan medan magnet pada panjang lokalisasi, density of state DOS , dan karakteristik I-V. Sifat transport muatan dipelajari dengan menghitung probabilitas transmisi, karakteristik I-V, dan memberikan pengaruh medan listrik dan medan magnet. Pada molekul DNA aperiodik, dipelajari pengaruh nilai hopping inter-strand terhadap probabilitas transmisi dan karakteristik I-V. Probabilitas transmisi dihitung dengan metode transfer matriks, sedangkan karakteristik I-V dihitung dengan formula Launder-Buttiker. Pada molekul DNA G4, dipelajari pengaruh medan listrik dan medan magnet terhadap panjang lokalisasi, density of state DOS, dan karakteristik I-V. Panjang lokalisasi dihitung menggunakan metode transfer matriks, dan density of state DOS serta karakteristik I-V dihitung dengan metode fungsi Green.

---

ABSTRACTThe charge transport of aperiodic DNA and G4 DNA molecule have been studied. On the aperiodic DNA molecule, the effect of the inter-strand hopping value on the I-V characteristic has been studied. The effect of the electric and magnetic field on the localization length, density of state (DOS), and I-V characteristics were studied G4 DNA molecule. Charge transport was studied by calculating the transmission probability, the I-V characteristic, by considering the effect of the electric and the magnetic field. In the aperiodic DNA molecule, we study the effect of hopping inter-strand on transmission probability and I-V characteristics. The transmission probability was calculated by the matrix transfer method, while the I-V characteristic was calculated by the Launder-Buttiker formula. In G4 DNA molecule, we studied the effect of the electric and magnetic field on the localization length, density of state (DOS), and I-V characteristic. Localization length was calculated using matrix transfer method, and density of state (DOS) and I-V characteristic was calculated by Green function method."

"Sifat transpor muatan pada molekul DNA untai ganda dan DNA G4 telah dipelajari. Kami menggunakan dua model DNA yang direpresentasikan secara matematis dengan menggunakan model Hamiltonian tight binding. Model yang pertama adalah DNA untai ganda dengan panjang 32 pasangan basa yang disusun secara random. Transpor muatan untuk molekul DNA ini dipelajari dari probabilitas transmisi dan karakteristik I-V dengan memvariasikan hopping elektron inter-strand tegak lurus. Peningkatan hopping electron inter-strand tegak lurus menyebabkan probabilitas transmisi dan arus meningkat, tetapi saat temperaturnya dinaikkan probabilitas transmisi dan arus menurun. Model kedua adalah DNA G4, Sifat transpor muatan pada molekul ini dipelajari dari panjang lokalisasi dengan panjang 102 pasangan basa, density of states dan karakteristik I-V masing-masing dengan 32 tumpukan tetrad guanin, yang diberi pengaruh medan listrik dan temperatur, Probabilitas transmisi dan panjang lokalisasi dihitung menggunakan metode transfer matriks. Formula landauer Buttiker digunakan untuk menghitung karakteristik I-V. Metode fungsi green untuk menghitung probabilitas transmisi dan density of states. Hasil perhitungan medan listrik dan temperatur terhadap sifat transpor muatan yaitu menurunkan panjang lokalisasi, density of states, dan arus, saat meningkatnya medan listrik dan temperatur.

---

The charge transport property on double-stranded DNA and G4 DNA molecules has been studied. We use two DNA models that are mathematically represented using Hamiltonian tight binding models. The first model is double stranded DNA with length of 32 base pairs arranged randomly. The charge transport for this DNA molecule is studied from transmission probabilities and I-V characteristics by varying of electron hopping in perpendicular inter-strand. Increased of electron hopping in perpendicular inter-strand causes the transmission and current probabilities to increase, but when temperature is increased the transmission probabilities and current is decrease. The second model is DNA G4. The charge transport property in this molecule is studied from localization length with length of 102 base pairs, density of states and I-V characteristics with 32 stacks of guanine tetrads respectively that influenced of electric field and temperature. Transmission probability and localization length are calculated using matrix transfer method. The buttiker landauer formula is used to calculate the I-V characteristics. Green function method for calculating transmission probability and density of states. The result of electric field and temperature calculation on charge transport leads to decreasing localization length, density of states, and current, when increasing of electric field and temperature."

"

Diantara tiga struktur TiO₂, anatase TiO₂ telah mendapat banyak perhatian karena sifatnya yang menarik serta potensinya untuk dimanfaatkan dalam berbagai aplikasi. Berbagai aplikasi tersebut bergantung pada sifat transpor material ini. Beberapa penelitian terdahulu mengenai sifat transport anatase TiO₂ menunjukkan adanya kopling antara elektron dan fonon yang membentuk suatu kuasi partikel bernama polaron. Namun, belum ada penjelasan mengenai bagaimana keberadaan polaron pada anatase TiO₂ mempengaruhi sifat transpor terutama resistivitas. Oleh karena itu, kami melakukan studi teoretik terhadap sifat transport anatase TiO₂ yang dipengaruhi oleh kehadiran polaron. Kami menggunakan model Holstein, di mana menggunakan dua pita anatase TiO₂ yaitu pita konduksi dan pita valensi yang diselesaikan dalam kerangka Dynamical Mean Field Theory (DMFT) untuk menjelaskan interaksi antar elektron dan fonon. Kami menghitung densitas keadaan sistem dan nilai dari invers kuadrat dari densitas keadaan yang berkorespondensi pada potensial kimia, di mana nilai ini sebanding dengan nilai resistivitas, sebagai fungsi temperatur. Dengan menggunakan nilai densitas pembawa muatan seperti pada eksperimen, hasil perhitungan menunjukkan pada resistivitas turun seiring dengan pertambahan temperatur pada seluruh nilai densitas pembawa muatan. Hal ini menunjukkan bahwa model yang digunakan hanya baik dalam mendeskripsikan efek trapping namun kurang baik dalam menjelaskan efek hamburan.

---

We present a theoretical study on the effects of electron-phonon interactions on the transport properties of anatase TiO₂. Temperature-dependent resistivity measurement on anatase TiO₂ thin film has shown that carrier concentrations and temperatures affect the resistivity of this material. At low carrier concentrations, a metal to insulator transition could be observed, while at high carrier concentrations this material only shows metal-like resistivity. In this study we aim to investigate the behavior of temperature-dependent resistivity at various carrier concentrations as revealed in the experimental study. We hypothesize that electron-phonon interactions with intermediate coupling constant govern the transport properties of this material. We construct Holstein model Hamiltonian incorporating both conduction and valence bands of anatase TiO₂ within parabolic dispersion approximation. We solve the model within the Dynamical Mean Field Theory (DMFT). We calculate the density of states of the system and the corresponding inverse of the square of the density of states at the chemical potential, which is approximately proportional to the resistivity, as a function of temperature. Using carrier concentration values taken as in the experimental data, the calculations show that only the trends of decreasing resistivity with increasing temperature is found in all carrier concentrations value. The results show that our model is good in the describing the trapping effects due to the electron-phonon interaction but the model is doing poorly in capturing the scattering effects.

 

"

"Sel surya merupakan divais elektronika yang dapat mengubah energi cahaya menjadi energi listrik. Saat ini Indonesia memiliki banyak hasil bumi salah satunya timah. Timah merupakan bahan dasar dalam pembuatan berbagai komponen elektronika, salah satunya electron transport layer (ETL) dari sel surya perovskite. Sel surya perovskite pada umumnya menggunakan TiO2 sebagai ETL yang memiliki work function sebesar -4,1 eV. SnO2 memiliki work function yang lebih besar, yaitu -4 eV; sehingga secara teori SnO2 dapat menggantikan TiO2. Penelitian ini menguji penggunaan timah pada sel surya perovskite sebagai ETL. Timah yang digunakan diambil dari bahan timah (II) klorida dihidrat. Timah (II) klorida dihidrat akan dilarutkan menggunakan ethanol. Struktur sel surya perovskite yang digunakan adalah FTO/SnO2/Perovskite/karbon aktif/FTO. Sel surya perovskite dalam penelitian ini tidak menggunakan hole transport layer (HTL) karena sifat dari karbon aktif yang menggunakan minyak paraffin sebagai perekat dapat berperan sebagai HTL. Penelitian pra skripsi menunjukkan ethanol merupakan pelarut yang lebih baik dari thiourea, dengan Isc = 0,0015 mA; Voc = 0,1 mV; dan FF = 0,4. Skripsi ini meneliti lebih jauh terhadap dampak konsentrasi SnO2 pada larutan prekursor dengan melakukan variasi pada jumlah timah (II) klorida dihidrat yang dicampur ke ethanol. Hasil fabrikasi menunjukkan bahwa sel surya perovskite dengan pencampuran 30 mg timah (II) klorida dihidrat dengan 1 ml ethanol menghasilkan Isc dan Voc yang paling baik, yaitu Isc = 0,19 mA dan Voc = 0,177 V; namun tidak memiliki konsistensi yang baik dan memiliki dark IV curve linear, menandakan unjuk kerja yang buruk. Sampel C yang dibuat dari pencampuran 20 mg timah (II) klorida dihidrat dengan 1 ml ethanol menunjukkan konsistensi yang baik dan dark IV cruve yang baik. Sampel C memiliki Isc = 0,033 mA; Voc = 0,026 V dan FF= 0,538.

---

Solar cell is an electronic device that convert solar energy into electrical energy. Indonesia has enormous amount of tin, that responsible for producing several amount of electrical device, electron transport layer (ETL) is one of them. Perovskite solar cell frequently uses TiO2 as an ETL that has work function -4.1 eV. SnO2 has better work function, -4 eV; that make SnO2 can become replacement for TiO2 theoritically. This research test the usage of tin on solar cell perovskite as an ETL. Tin derived from tin (II) choride dihydrate, that will be mixed with ethanol. Perovskite solar cell structure used is FTO/SnO2/Perovskite/activated carbon/FTO. In this research, perovskite solar cell did not use hole transport layer (HTL) because of the nature of activated carbon using paraffin oil as an adhesive to act as a HTL. Pra Skripsi shows the best result is obtained from SnO2 that used ethanol as precursor, with Isc = 0.0015 mA, Voc = 0.1 mV, and FF = 0.4. This research concentrate on variating the amount of tin (II) chloride dihydrate that mixed with ethanol. Perovekite solar cell with mixture of 30 mg tin (II) chloride dihydrate with 1 ml ethanol produce Isc = 0.19 mA and Voc = 0.177 V that has best Voc and Isc; but lack of concintency and has linear dark IV curves, resulting on bad performance. Sampel C obtained from 20 mg tin (II) choride dihydrate with 1 ml ethanol shows better consistency, FF and better IV curve. with Isc = 0.033 mA; Voc = 0.026 V and FF= 0.538."

"Discover the link between the latest chemical biology approaches and novel drug therapies! Protein Targeting with Small Molecules: Chemical Biology Techniques and Applications takes readers beyond the use of chemical biology in basic research, providing a highly relevant look at techniques that can address the challenges of biology and drug design and development. This indispensable bench companion features up-to-date coverage of advances in chemistry and assesses their impact on developing new therapeutics, making it ideal for chemical biologists and medicinal chemists who are developing small molecule drugs to target proteins and treat diseases. In addition, the book examines the full range of complex biological systems and their interrelationship with chemistry, from the interaction of biological response modifiers with proteins to the chemical biology of cell surface oligosaccharides. Distinguished by an overview of chemical biology that is reinforced and clarified by detailed examples and descriptions of techniques, Protein Targeting with Small Molecules: Chemical Biology Techniques and Applications:* Introduces key technologies and methods of chemical biology designed to detect the interactions of small molecules and proteins* Facilitates the discovery of small molecules that bind to proteins and describes the molecules' application in the investigation of biological processes* Presents timely coverage of the development of fluorescent probes for small molecules, as well as the generation of small molecule ligands and inhibitors* Reviews important techniques such as chemical genomics, target profiling, immobilization technology, detection methods, chemical inhibition, and structure-based targeting* Offers a compelling synopsis of data that underscores the recent progress made in the area of targeting proteins by small molecules"

"Malnutrisi sering ditemukan pada anak dengan pasca pembedahan dan berhubungan dengan luaran sepsis atau infeksi luka operasi. Penelitian observasional analitik ini bertujuan mengetahui pengaruh malnutrisi terhadap luaran pasien pasca pembedahan dengan mengukur penurunan kadar RBP pada hari pertama dan kelima pasca pembedahan. Dilakukan pengukuran kadar RBP, kortisol, CRP pada hari pertama dan kelima pasca pembedahan, luaran infeksi dinilai berdasarkan skor ASEPSIS. Hasil penelitiaan ini menunjukkan penurunan RBP, peningkatan CRP, usia dan skor ASA berturut-turut memberikan risiko 4,4;3,3;1,2 dan 1,3 kali terjadinya infeksi luka operasi pada pasien pasca pembedahan mayor, namun tidak didapatkan perbedaan yang bermakna.

---

Malnutrition is often found in children with post-surgery and associated with poor outcomes such as sepsis or surgical wound infections. This analytic observational study aims to determine the effects of malnutrition on the outcomes of patients after surgery by measuring the decrease in Retinol Binding Protein (RBP) levels on the first and fifth day post-surgery. We measured levels of RBP, cortisol, CRP in the first and fifth day post-surgery and infection outcomes were evaluated according to ASEPSIS score. The results of this study showed a decrease in RBP, an increase in CRP, age and ASA score consecutively provide risk 4.4; 3.3, 1.2 and 1.3 times for occurrence of surgical wound infections in patients after major surgery, but there were no statistically differences."