Hasil Pencarian  ::  Simpan CSV :: Kembali

"Paduan aluminium 2024-T3 biasa digunakan dalam industri penerbangan seperti komponen pada pesawat terbang. Material ini digunakan karena sifatnya yang ringan dan cenderung tahan korosi jika dibandingkan dengan material selain aluminium, namun jika dibandingkan dengan paduan aluminium seri lainnya, paduan aluminium 2xxx cenderung memiliki ketahanan korosi yang rendah. Untuk memperbaiki sifat ini, maka dilakukan proses anodisasi dengan larutan elektrolit asam oksalat 0,5 M selama 30 menit. Proses anodisasi dilakukan pada temperatur 0, 10, dan 20°C serta rapat arus 15, 20, dan 25 mA/cm2. Penelitian bertujuan untuk mengetahui pengaruh dari kedua variabel tersebut terhadap kekerasan mikro dan laju korosi tiap sampel. Didapat hasil bahwa nilai kekerasan mikro paling tinggi pada permukaan sampel didapat pada sampel 0°C - 20 mA/cm2 dengan nilai kekerasan sebesar 543 HV. Sedangkan ketahanan korosi paling baik diperoleh pada sampel 20°C - 20 mA/cm2 dengan laju korosi sebesar 0,00004 mm/year.

---

Aluminum alloy 2024-T3 is commonly used in the aviation industry as components of aircrafts. This material is used because of its light weight and good corrosion resistant when compared to material other than aluminum, but when compared to other series of aluminum alloy, aluminum alloy 2xxx tend to have low corrosion resistance. To improve this property, then carried out the anodizing process with 0,5 M oxalic acid for 30 minutes. Anodizing was carried out at temperatures of 0, 10, and 20°C also at current densities of 15, 20, and 25 mA/cm2.

The research aim is to know the influence of both these variables against the corrosion rate and micro-hardness of each samples. The result shows that the highest micro-hardness on the surface of samples is obtained at 0°C and 20 mA/cm2 with a value of 543 HV. While the most excellent corrosion resistance is obtained at 20°C and 20 mA/cm2 with the rate of corrosion of 0,00004 mm/year."

"KARAKTERISASI LAPISAN PENYERAP DAPAT BAKAR PADA PERMUKAAN PELET UO2 + DOPAN TiO2. Lapisan penyerap dapat bakar pada permukaan pelet UO2 + dopan TiO2 telah berhasil dibuat dengan menggunakan mertoda RF sputtering. Penelitian ini bertujuan untuk mendapatkan karakter mikrostruktur pelet UO2 + dopan, ketebalan, kekerasan mikro, komposisi kimia dan struktur kristal lapisan penyerap dapat bakar pada permukaan pelet UO2. Penentuan mikrostruktur dan ketebalan lapisan dilakukan dengan menggunakan mikroskop optik, kekerasan lapisan dengan metode kekerasan mikro Vickers, komposisi kimia dengan spektrometri XRF dan struktur kristal dengan difraksi sinar-X. Hasil penelitian menunjukan bahwa semakin besar kandungan TiO2 dalam pelet maka semakin besar ukuran butir dalam mikrostruktur pelet dan semakin tebal lapisan yang terbentuk pada permukaan pelet UO2. Kekerasan lapisan permukaan pelet UO2 + dopan TiO2 sinter relatif sama dan tidak bergantung pada konsentrasi dopan TiO2. Lapisan permukaan pelet UO2 + 0,3 % TiO2, pelet UO2 + 0,5 % TiO2 dan pelet UO2 + 0,7 % TiO2 sinter mengandung unsur zirkonium masing-masing 1,97 mg, 2,47 mg dan 4,81 mg. Lapisan penyerap dapat bakar pada permukaan pelet UO2 + dopan TiO2 sinter mempunyai fasa ZrB2 dengan struktur kristal heksagonal.CHARACTERIZATION OF BURNABLE ABSORBER LAYER ON THE SURFACE OF UO2 + DOPED TiO2 PELLETS. Burnable absorber layer on the surface of UO2 + doped TiO2 pellets have successfully created using RF sputtering methods. The objective of this research is to obtain of microstructure characters of UO2 + doped TiO2 pellets, thickness, micro hardness, chemical composition and crystal structure of burnable absorber layer on the surface of UO2 pellets. The methods used are the microstructure and layer thickness using optical microscopy, layer hardness with micro Vickers hardness method, chemical composition by XRF spectrometry, and crystal structure by X-ray diffraction. The results showed that the larger of TiO2 content in the pellets then the greater of the grain size in the microstructure of the pellets and the thicker of the layer formed on the surface of UO2 pellets. The hardness of surface layer of UO2 + doped TiO2 sintered pellets are equal and does not depend on the dopant concentration of TiO2. The surface layer of UO2 + 0.3 % TiO2, UO2 + 0.5 % TiO2 and UO2 + 0.7 % TiO2 sintered pellets are containing zirconium respectively 1.97 mg, 2.47 mg and 4.81 mg. Burnable absorber layer on the surface of UO2 + doped TiO2 sintered pellets have ZrB2 phase with a hexagonal crystal structure."

"Austenit sisa bersifat metastabil pada suhu ruang sehingga dapat bertransformasi menjadi martensit sehingga menyebabkan delayed crack, yang terjadi setelah beberapa lama proses produksi, pada bucket tooth excavator dengan material baja HSLA. Penelitian ini berfokus pada proses perlakuan panas yang dilakukan, yaitu pada tahapan austenisasi. Austenisasi dilakukan pada temperature 926°C dengan variable waktu tahan 28 menit, 43 menit, 58 menit, dan 73 menit. Sampel pengujian awalnya berupa keel block hasil normalisasi temper, yang kemudian dipotong menjadi balok dengan dimensi 4x1x4 cm. Karakterisasi dilakukan pada sampel as-QTT dan setelah ditempering, dimulai dari pengamatan struktur mikro menggunakan mikroskop optic dan Scanning Electron Microscope (SEM), serta pengujian kekerasan mikro (microvickers) dan kekerasan makro (Rockwell C). Setelah diamati, diperoleh bahwa sampel baja as-QTT memiliki struktur mikro yang didominasi oleh tempered martensit, namun ditemukan juga keberadaan lower bainite dan sejumlah kecil austenite sisa. Semua variabel temperatur tempering menghasilkan bentuk struktur mikro yang sama, namun memiliki presentase austenite sisa yang berbeda-beda. Seiring bertambahnya waktu tahan austenisasi, ukuran butir dan martensite menjadi semakin kasar. Kekerasan baja mengalami peningkatan seiring bertambahnya waktu austenisasi yaitu dari 486 HV menjadi 522 HV pada waktu tahan 58 menit, lalu menurun menjadi 450 pada waktu tahan 73 menit.

---

ABSTRACTRetained Austenite is metastable at room temperature so that it can be transformed into martensite, causing delayed cracks, which occur after a long time of the production process, on bucket tooth excavators with HSLA steel material. This research focus on the heat treatment process carried out, especially in the austenitizing stage. Austenitizing was carried out at a temperature of 926°C with a variable holding time of 28 minutes, 43 minutes, 58 minutes, and 73 minutes. Initially the test sample was a tempered normalized keel block, which was then cut into blocks with dimensions of 4x1x4 cm. Characterization is carried out on as-QTT samples and after tempering, starting from observing microstructure using optical microscopy and Scanning Electron Microscope (SEM), as well as testing micro hardness (microvickers) and macro hardness (Rockwell C). After observing, it was found that the as-QTT steel sample had a micro structure dominated by tempered martensite, but the presence of lower bainite and a small amount of remaining austenite was also found. All tempering temperature variables produce the same microstructure, but have different residual austenite percentages. As the austenisation holding time increases, grain size and martensite become increasingly coarse. The hardness of steel has increased with increasing austenisation time from 486 HV to 522 HV at 58 minutes holding time, then decreased to 450 at 73 minutes holding time."

"Tujuan umum: Mengetahui profil keamanan dan efek getah J. curcas terhadap jaringan gigi dan periapeks dalam persiapan untuk memanfaatkan pemakaian bahan alami getah J. curcas pada radang pulpa. Tujuan khusus (1) Mengetahui kandungan golongan senyawa getah J. curcas. (2) Mengetahui sitotoksisitas getah J. curcas. (3) Mengetahui toksisitas akut pemberian secara oral dosis tunggal getah J. curcas pada hewan percobaan. (4) Mengetahui aktivitas hemolisis getah J. curcas pada darah manusia secara in vitro. (5) Mengetahui sifat mutagenisitas getah J. curcas. (6) Mengetahui efek getah J. curcas terhadap pembebasan interleukin-1β oleh sel makrofag. (7) Mengetahui efek getah J. curcas terhadap pembebasan kolagenase pada set fibroblast. (8) Mengetahui efek histopatologik getah J. curcas terhadap pulpa dan jaringan periapeks gigi pada hewan percobaan. (9) Mengetahui efek getah J. curcas terhadap kekerasan macro jaringan keras gigi manusia secara in vitro. (10) Mengetahui efek getah J. curcas terhadap jaringan keras gigi manusia dalam hal kelarutan unsur kalsium dan fosfat secara in vitro. Metode penelitian: Disain penelitian eksperimental dan eksplorasi. Penelitian dibagi atas (1) skrining fitokimia, (2) tahap 1 dan (3) tahap 2 evaluasi biologik getah J. curcas. Untuk standardisasi getah J. curcas diambil dari satu petak tanaman dalam satu musim, kemudian diukur pH, volume basah, diliofilisasi, diukur berat kering, dan disimpan pada -20°C sebagai sampel. (1). Skrining fitokimia getah J. curcas. Analisis kualitatif golongan senyawa diidentifikasi dari ekstrak eter, etil asetat, dan air. (2). Uji toksisitas 1. Uji sitotoksisitas. (1) Metoga agar overlay. Getah J. curcas dan kontrol diserap oleh cakram selulosa, kemudian diletakkan di atas permukaan agar yang menutupi selapis sel Fib L929 yang telah diwarna neutral red. Evaluasi berdasar luas zona dekolorisasi dan zona lisis yang terbentuk setelah 24 jam. (2) Assay MTT. Getah J. curcas dalam medium diberikan pada kultur set Fib L929 cell line dan sel primer fibroblast gingiva manusia yang tumbuh dalam mikroplat 96-sumur. Setelah 1-4 hari, dilakukan assay MTT. Evaluasi berdasar perbandingan nilai OD kontrol dan perlakuan. 2. Uji toksisitas akut. Mencit diberi getah J. curcas secara intragastrik sebanyak 1 kali. Dihitung LD5O berdasar jumlah mencit yang mati. Dibandingkan antara kelompok perlakuan dan kontrol dalam hal tanda toksisitas, berat badan selama 2 minggu, pemeriksaan makroskopik dan mikroskopik organ tubuh. 3. Uji hemolisis. Darah dicampur dengan berbagai konsentrasi getah J. curcas. Evaluasi berdasar pembebasan hemoglobin, dibandingkan OD kelompok perlakuan dengan kontrol positif air, dan kontrol negatif salin. 4. Uji mutagenisitas. Getah J. curcas dikultur dengan bakteri S. typhi dan E. coil mutan. Evaluasi berdasar penghitungan koloni reversi bakteri, dibandingkan kelompok perlakuan, kontrol positif dan kontrol negatif. (3) Efek getah J. curcas terhadap makrofag dan fibroblast 1. Efek getah J. curcas terhadap pembebasan IL-1β. Lima dosis getah J. curcas dimasukkan ke dalam kultur makrofag peritoneum mencit BALB/c, secara bersamaan, sebelum, atau sesudah pemberian LPS. Setelah 1 dan 2 hari, IL-1β dalam supernatan diukur secara ELISA dengan Quantikine IL-1β for mouse kit. 2. Efek getah J. curcas terhadap pembebasan kolagenase oleh fibroblast. Empat dosis getah J. curcas dan IL-1β dimasukkan dalam kultur sel primer fibroblast gingiva manusia. Setelah 1-4 hari kolagenase dalam supematan diukur dengan assay kolagenase. Hasil degradasi kolagen dipisahkan dengan SDS-PAGE. Pita 3/4 αA diukur dengan program komputer Adobe Photo. (4) Efek histopatologik getah J. curcas pada jaringan pulpa dan periapeks. Getah J. curcas dimasukkan ke dalam kavitas gigi monyet. Setelah 3 hari, gigi diproses untuk pembuatan sediaan histologik. Evaluasi berdasar perbandingan pemeriksaan keadaan mikroskopik jaringan pulpa dan peripeks dalam hal inflamasi dan nekrosis, antara kelompok kontrol dan perlakuan. (5) Efek getah J. curcas terhadap jaringan keras gigi. 1. Efek getah J. curcas terhadap kekerasan mikro dentin dan email. Mahkota gigi premolar dibelah 4 longitudinal, lalu ditanam di dalam akrilik dengan 1 permukan tidak tertutup akrilik. Setelah direndam dalam 3 konsentrasi getah J. curcas, permukaan dentin dan email diberi indentasi oleh intan Knoop. Evaluasi berdasar perbandingan KHN kelompok kontrol dan perlakuan. 2. Efek getah J. curcas terhadap kelarutan kalsium dan fosfat. Mahkota gigi premolar utuh dibelah 4 secara longitudinal, lalu direndam dalam 3 konsentrasi getah J. curcas. Setelah 1-3 hari, kalsium dan fosfat yang larut dalam rendaman diukur berturut-turut dengan alat atomic absorption spectrophotometer (AAS) dan spektrofotometer (metoda asam askorbat). Hasil penelitian pH getah J. curcas rata-rata 3,49 ± 0,09 dan perbandingan berat kering/volume basah 15,12 ± 0,31%. (1) Skrining fitokimia: getah J. curcas mengandung golongan senyawa sterol, aglikon flavon, tanin, senyawa pereduksi, glikosida steroid, poliose, dan saponin. (2) Uji toksisitas 1.(1) Sitotoksisitas getah J. curcas pada metoda agar overlay ditemukan zona dekolorisasi indeks 2 dari 5 indeks zona. Tak ada lisis sel, bentuk sel masih jelas. (2) Assay MTT: pads getah J. curcas kadar 0,25% terhadap Fib L929 dan kadar 0,12% terhadap fibroblast gingiva, sel nekrosis. 2.(1) LD50 > 5 g/kg BB, sehingga getah J. curcas dapat diklasifikasi dalam toksik ringan. (2) Tidak ada perbedaan berat badan. (3) Tidak ada perbedaan makroskopik dan mikroskopik organ tubuh yang diperiksa. (4) Terjadi inaktivitas pada hari 1 pada kelompok perlakuan, selanjutnya tidak ada perbedaan. 3. Aktivitas hemolisis getah J. curcas 15% adalah 6,5% dibanding air. Tidak ada hemolisis pada konsentrasi getah J. curcas yang lebih rendah. 4. Tidak ada aktivitas mutagenisitas getah J. curcas. (3) Efek getah J. curcas terhadap makrofag dan fibroblast 1. (1) LPS meningkatkan pembebasan 1L-1β oleh makrofag. (2) Pemberian getah J. curcas menghambat pembebasan 1L-1β oleh makrofag. 2. (1) Makin lama waktu kultur, produksi kolagenase makin banyak. (2) Getah J. curcas menurunkan pembebasan kolagenase oleh fibroblast. (4) Efek histopatologik getah J. curcas terhadap jaringan pulpa dan periapeks (1) Inflamasi dan nekrosis terj adi pads daerah yang terbatas dekat dengan daerah yang kontak dengan getah J. curcas. Di bawahnya terdapat jaringan pulpa normal. (2) Tingkat inflamasi pulpa kelompok perlakuan tidak lebih parah dari kelompok kontrol. (3) Tidak ada radang periapeks pads kelompok kontrol dan perlakuan. (5) Efek getah J. curcas terhadap jaringan keras gigi. 1. Efek getah J. curcas terhadap kekerasan mikro dentin dan email. (1) Kekerasan mikro dentin tidak berbeda bermakna pada 1 dan 2 hari perendaman getah J. curcas antara kelompok kontrol dan perlakuan. Namur lebih kecil setelah 3 hari pada konsentrasi getah 15%. (2) Kekerasan mikro email tidak berbeda antara kelompok kontrol dan perlakuan pada 1 dan 3 hari, Namun lebih kecil setelah 2 hari pada konsentrasi getah J. curcas 15%. 2. Kadar kalsium dan fosfat yang larut meningkat sesuai dengan kenaikan konsentrasi getah J. curcas. Namun lama perendaman tidak berpengaruh secara bermakna terhadap kelarutan kalsium. Kesimpulan (1) Getah J. curcas mengandung sterol, aglikon flavon, tanin, senyawa pereduksi, glikosida steroid, poliose, dan saponin. (2) Tahap 1 evaluasi biologik: getah J. curcas relatif aman pada hewan percobaan berdasar LD50>5 g/kg BB sehingga termasuk dalam klasifkasi toksik ringan; hemolisis 6,5% dibanding air; tidak mutagen; dan sitotoksik dengan nekrosis koagulasi. (3) Uji tahap 2: getah J. curcas cukup efektif dalam menanggulangi pulpalgia, berdasar nekrosis pulpa terbatas, tidak ada kelainan periapeks; kekerasan mikro email dan dentin tidak turun pada 1 hari; menghambat pembebasan IL-1β dan kolagenase. Namun getah melarutkan kalsium dan fosfat. Kesimpulan penelitian: penelitian dapat dilanjutkan ke tahap uji klinik atau tahap 3.

---

Biological Study on the Effects of Jatropha Curcas (Euphorbiaceae) Latex on Dental and Periapical TissuesObjective: The objective of this study was to evaluate the safety level and the effects of J. curcas latex on dental and periapical tissues. The aims in details were (1) to identify the main classes of chemical constituent in J. curcas latex; (2) to evaluate the cytotoxicity of J. curcas latex; (3) to determine the acute toxicity of J. curcas latex after single oral administration on mice; (4) to assess hemolytic activity of J. curcas latex; (5) to evaluate mutagenic activity of J. curcas latex; (6) to evaluate the effect on J. curcas latex of IL-1 il release from macrophages; (7) to evaluate the effect of J. curcas latex on collagenase release from fibroblasts; (8) to assess the histopathological effects of J. curcas latex on monkey dental pulp and periapical tissues; (9) to determine the effects of J. curcas latex to dentin and enamel micro-hardness; (10) to assess the effects of J. curcas latex on dissolving calcium and phosphate. Methods: Research design was experimental and explorative. To standardize the sample, J. curcas latex was collected from Balittro, Bogor in 1997, then the pH and wet volume were measured, the latex was lyophilized, dry weight was measured, and latex was stored at-20°C as sample. Biological evaluation was grouped into (1) phytochemical sreening, (2) toxicity test, (3) effects of J.curcas latex on cell, (4) effects of J.curcas latex on dental pulp and periapical tissues, and (5) effects of J.curcas latex on dental hard tissues, (1). Phytochemical screening: the main classes of chemical constituents of J. curcas latex were analyzed qualitatively from ether, ethyl acetate, and water extracts. (2). Toxicity test 1. Cytotoxicity test. (1) Agar overlay technique. J. curcas latex was imbibed in cellulose discs and put on the surface of agar overlaying a neutral red stained Fib L929 cell monolayer. Evaluation was judged on zone index and lysis index after 24 hours incubation. (2) MT assay. J. curcas latex was added to human gingival fibroblasts and Fib L929 cell culture in 96-well micro-plates. After 1-4 days of incubation, MTT assay was performed. Evaluation was based on comparing the OD values of control and test groups. 2. Acute toxicity. A single dose of J. curcas latex was given to male and female mice, intragastrically. LD50 was determined based on mortality rate. Assessment was also performed on 2 weeks observations of body weight, macroscopic and microscopic examinations of several organs. 3. Hemolysis test. Blood was mixed with several concentrations of J. curcas latex. The result was the extent of hemolysis expressed based on the absorbance of the test samples, negative and positive controls. 4. Mutagenicity test. L curcas latex was added to the S. ryphi and E. coil mutans culture. Assessment was based on bacterial revertant colonies, compare to positive and negative controls. (3) Effects of J.curcas latex on macrophages and fibroblasts 1. Effects of .T. curcas latex on the release of IL-1 β from macrophages. Five doses of J. curcas latex from 75-1200 μg/ml were added into the culture of BALB/c mice peritoneal macrophages, along with, after, or before addition of LPS. Following 1-3 days of incubation, IL-1P presence in supernatant was measured by ELISA using Quantikine ]L-1P for mouse kit. 2. Effects of J. curcas latex on the release of collagenase. Four doses of J. curcas latex from 37.5-300 µg/ml were added to human gingival fibroblasts cell culture. After 1-4 days of incubation, collagenase in the supernatant was assayed with collagen. The degradation products were then separated by SDS-PAGE and the density of 3/4 αA bands was measured semi quantitatively by Adobe Photo computer program. (4) Effects of J.curcas latex on dental pulp and periapical tissues. The latex of J. curcas was brought in contact with dental pulp and sealed. Assessment was based on the presence of inflammation and necrosis in dental pulp and periapical tissues, histopathologically. (5) Effects of J.curcas latex on dental hard tissues 1. Effects of J. curcas latex on dentin and enamel micro-hardness. Intact premolar crowns were cut longitudinally into 4 fragments, followed by embedding of each fragment in acrylats leaving 1 free surface. The fragments were then soaked in 3 concentrations of J. curcas latex from 3.7-15% for 1-3 days. The dentin and enamel micro-hardness were assessed by Knoop hardness measurement. 2. Effects of J. curcas latex on dissolved calcium and phosphate. Intact premolar crowns were cut longitudinally into 4 fragments, followed by soaking the fragments in 3 concentration of J. curcas latex from 3.7-15% for 1-3 days. The dissolved calcium and phosphate were measured according to atomic absorption spectrophotometer and spectrophotometer (ascorbic acid method), respectively. Results: The mean ± SD of J. curcas latex pH was 3.49 ± 0.09. The dry weight/wet volume was 15.12 ± 0.31%. (1). Phytochemical screening: sterols, flavone aglycones, tannins, reducing compounds, sterol glycosides, poliose, and saponins were identified in J. curcas latex. (2) Toxicity test 1. (1) Agar overlay technique. 2-5 mm decoloration zones were observed, indicating that J. curcas latex was cytotoxic. No lysis of cells was observed within the decolorized zone. (2) MTT assay. At 2.5 mg/ml J. curcas latex no living Fib L929 cells were observed, while the same result was shown at 1.2 mg/ml J. curcas latex on human gingival fibroblasts. 2. LD50 was more than 5 g/kg BW, hence dry J. curcas latex may be classified into mildly toxic substance. No significant body weight difference was observed. Macroscopic and microscopic examination on several organs showed no differences between test and control groups. 3. 6,5% hemolytic activity of 15% J. curcas latex compared to water was observed, while no hemolisis was observed with lower concentrations of latex. 4. No mutagenic ativity was observed with J. curcas latex. (3) Effects of J.curcas latex on macrophages and fibroblasts 1. (1) LPS increased the release of IL-1β. (2) J. curcas latex inhibited the release of IL-lβ from macrophages. 2. (1) The longer the duration of incubation, the more collagenase was released. (2) J. curcas latex decreased collagenase release by human gingival fibroblast. (4) Effects of I. curcas latex on dental pulp and periapical tissues. Inflammation and necrosis were observed in a limited area, which was in direct contat with J. curcas latex, underneath was normal pulp. Inflammation in the pulp of test group was not greater than in the control group. No inflammation or necrosis in periapical tissues was observed in all groups. (5) Effects of J. curcas latex on dental hard tissues 1. (1) The micro-hardness of dentin was not lowered after 1 and 2 days treatment, but lower after 3 days at 15% J. curcas latex. (2) The enamel microhardness was not decreased after 1 and 3 days immersion in J. curcas latex, but decreased after 2 days at 15% J. curcas latex. 2. The calcium and phosphate release were increased in accordance to the concentration of J. curcas latex. The duration of treatment did not influence the release of calcium, while it influenced the release of phosphate. Conclusions (1) J. curcas latex contains sterols, flavone aglycones, tannins, reducing compounds, sterol glycosides, poliose, and saponins. (2) Level 1 biological evaluation: J. curcas latex is relatively safe in animals based on LD50>5 g/kg BW, 6,5% hemolysis compared to water, not mutagenic, but cytotoxic with coagulative necrosis. (3) Level 2 biological evaluation: J. curcas latex seems to be effective in relieving pulpal pain. It caused coagulative necrosis in pulp, which was in direct contact with J. curcas latex while the tissue underneath was normal. It did not cause inflammation of periapical tissues, and did not lower the dentin and enamel micro-hardness after 1 day of exposure, but it lowered the microhardness after 3 days. It inhibited IL-1β and collagenase release. It dissolved dental calcium and phosphate."