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"Kondisi kerja dari cetakan plastik menuntut ketahanan terhadap berbagai faktor eksternal yang kompleks. Kegagalan yang sering dihadapi adalah keausan permukaan, deformasi struktural, bahkan fraktur pada bagian tertentu. Cacat material yang umum terjadi pada proses pembuatan cetakan plastik adalah orange peel, yang merupakan cacat yang menghasilkan pola permukaan yang terlihat seperti kulit jeruk dengan lembah-lembah dan bukit-bukit yang acak menutupi sebagian besar permukaan. Metode penelitian yang dilakukan meliputi machining, preparasi sampel, perlakuan panas, karakterisasi sampel, dan pemolesan. Karakterisasi sampel meliputi uji komposisi, uji kekerasan, metallografi, dan uji kekasaran sebelum dan setelah perlakuan panas. Proses perlakuan panas merupakan suatu proses yang digunakan untuk mengubah sifat fisik dan mekanik dari suatu material, biasanya logam dan paduannya, dengan cara memanaskannya secara terkontrol kemudian mendinginkannya. Berdasarkan hasil pengujian, diperoleh nilai akhir Ra sebesar 0.02µm untuk permukaan yang telah dipoles. Nilai ini menunjukkan bahwa kekasaran permukaan telah berhasil ditingkatkan secara signifikan, yaitu mencapai tingkat kehalusan yang sangat tinggi karena memenuhi kriteria untuk mencapai mirror finish. Material 420 ESR telah memenuhi standar untuk pembuatan cetakan speedometer karena kandungan karbon bernilai 0.382wt%. Proses perlakuan panas berhasil menghasilkan kekerasan mencapai 56.6 HRC dengan kekuatan tarik yang mencapai kisaran 2070-2105 N/mm2.

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The working conditions of plastic molds demand resistance to various complex external factors. Failures often encountered are surface wear, structural deformation, and even fracture of certain parts. A common material defect in the plastic mold manufacturing process is orange peel, which is a defect that produces a surface pattern that looks like an orange peel with random valleys and hills covering most of the surface. The research methods include machining, sample preparation, heat treatment, sample characterization, and polishing. Sample characterization includes composition test, hardness test, metallography, and roughness test before and after heat treatment. The heat treatment process is a process used to change the physical and mechanical properties of a material, usually metals and their alloys, by heating it in a controlled manner and then cooling it. Based on the test results, the final Ra value of 0.02µm was obtained for the polished surface. This value indicates that the surface roughness has been significantly improved, reaching a very high level of smoothness as it meets the criteria for achieving a mirror finish. The 420 ESR material meets the standard for making speedometer molds because the carbon content is 0.382wt%. The heat treatment process successfully produced a hardness of 56.6 HRC with a tensile strength that reached the range of 2070-2105 N/mm2."

"ABSTRAKPada industri otomotif terdapat proses elektroplating sebagai bagian dariproses produksi. Proses ini menghasilkan limbah dengan kandungan logam nikelyang cukup tinggi kisaran 27,6 - 34,8 mg/L. Adsorpsi merupakan salah satualternatif pengolahan limbah secara fisik yang memiliki desain sederhana danmudah dalam pengaplikasiannya. Salah satu adsorben alami yang dapat dipakaiuntuk menyisihkan logam nikel adalah kulit buah jeruk lokal dari jenis jeruk siam(Citrus nobilis var microcarpa). Pada penelitian ini, percobaan adsorpsi dilakukansecara batch dengan metode two-level full factorial design untuk mendapatkanwaktu kontak dan dosis adsorben optimum. Dari hasil penelitian, kulit jerukberhasil dijadikan sebagai karbon aktif dengan nilai bilangan iodin sebesar 364,29mg/gr, nilai kadar air sebesar 2,9%, dan densitas sebesar 0,623 g/mL. Prosesadsorpsi secara batch dapat menyisihkan nikel sebanyak 18,3% dengan kombinasidosis adsorben optimum sebesar 36 g/L dan waktu kontak optimum 70 menit. Dataekuilibrium adsorpsi nikel menunjukkan kecocokan dengan model isothermFreundlich dengan nilai kapasitas adsorpsi sebesar qe = 0,23 mg/g. Data kinetikaadsorpsi menunjukkan kecocokan dengan pseudo-second order model dengan nilailaju kinetika knikel = 0,04 g/mg.menit.

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ABSTRACTIn the automotive industry there is an electroplating process as a part ofthe production process. This process produces a waste with nickel metal contentthat high enough with range of 27.6 to 34.8 mg/L. Adsorption is one of physicalwaste treatment alternative which has a simple design and easy to apply. One ofnatural adsorbent that can be used to reduce a nickel metal is local orange peel fromtangerine family (Citrus nobilis var microcarpa). In this study, an activated carbonsuccessfully made from orang peel with iodine number 364,29 mg/gr, water content2,9%, and density 0,623 g/mL. Batch adsorption experiments with two-level fullfactorial design method was conducted to get the optimum contact time andoptimum adsorbent dosage. From the result of this research, the batch adsorptioncan reduce 18,3% nickel with a combination of 36 g/L optimum adsorbent dose and70 minutes optimum contact time. Adsorption equilibrium data of nickel were bestfitted by Freundlich isotherm model with adsorption capacity values of qe = 0,23mg/g. Adsorption kinetics data were best fitted by the pseudo-second order kineticsmodel with a rate value knikel = 0,04 g/mg.minute."

"Azo dyes are the largest class of dyes used in industry, mainly in textile and paper making sectors. These compounds are difficult to be degraded biologically and in anaerobic environments could transforms into aromatic amine, which may be toxic and carcinogenic. This article discusses preliminary identification of degradation products of Orange II, an azo dye, by a fungus isolate Penicilium sp. L2 in aerobic conditions. The decolorization of Orange II in a laboratory scale batch process with an initial concentration of 0.1 g/l was completed after 74 hours of incubation. The degradation products was observed as three distinct spots on thin layer chromatography plates in solvent system of 1-propanol-water (25:75). Using the same mobile phase, the result of highperformance liquid chromatography analysis demonstrated that the number of intermediate products was increasing at a longer incubation time, up to a certain point, where some of these compounds were further decomposed. After 74 hours to 144 hours of incubation. Orange II has been transformed into at least five intermediate-products, separated at retention times of 4.14, 4.73, 6.03, 8.14, and 14.88 minutes, having maximum wavelengths of 207, 254, 227, 203, and 227 nm, respectively."

"Fabrikasi mikro telah digunakan untuk berbagai aplikasi di bidang engineering seperti micro gear, micro heat exchanger serta dapat diaplikasikan di bidang biologi dan kedokteran seperti micro needle, micro fluidic, dan bracket orthodontics. Penelitian yang dilakukan yaitu modifikasi permukaan pada material steel SKD 61 dengan metode etching untuk mendapatkan surface roughness kontur kedalaman mesh braket ortodontik menggunakan larutan FeCl3 sebagai etchant dengan berbagai variasi pola pocket lingkaran, pocket persegi channel heksagonal hasil maskless photolithography untuk mengetahui feasibility pembuatan mold braket ortodontik yang sesuai dengan kontur gigi dengan metode etching.Pada penelitian ini didapatkan bahwa secara keseluruhan nilai Ra tiap kenaikan waktu mengalami peningkatan, dengan range nilai Ra pocket yaitu 0,36 m - 0,74 m dan nilai Ra optimum 0,51 m sedangkan untuk channel dengan nilai Ra optimum 0, 63 m hampir mendekati Ra ideal pada braket ortodontik yaitu 0,53 m. Kedalaman optimum pada pocket yaitu 175,4 m dan channel 107,7 m mendekati kedalaman ideal pada braket ortodontik yaitu sebesar 150 m. Untuk nilai MRR dan SMRR tidak memiliki tren yang jelas karena naik dan turun setiap perubahan waktu. Surface yang terbentuk memiliki tren hasil pemakanan yang cenderung menghasilkan bentuk U dengan kondisi tidak mengerucut dibagian atas feasible untuk injection molding namun belum memiliki spesifikasi kontur dan kekasaran yang optimum sehingga metode etching memiliki potensi untuk di aplikasikan ke mold braket ortodontik.

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Micro fabrication has been used for many application at engineering such as micro gear, micro heat exchanger, also nowadays can be applied at biological or medic such as micro needle, micro fluidic and bracket orthodontics. The objective of research to modify the surface on steel SKD 61 material to get optimum surface roughness contour of mesh using FeCl3 as enchat with various pattern circle pocket, square pocket hexagonal channel of maskless photolithography to know the feasibility of mold bracket orthodontics fabrication that appropiate with teeth contour.From this research, the range of pocket Ra value 0,36 m 0,74 m and optimum Ra value is 0,51 m, then for channel has optimum Ra value 0,63 approxiamtely close to Ra value that needed on bracket orthodontics 0,53 m. The depth of pocket has optimum value 175,4 m, then channel has optimum value 107,7 m close to optimum depth value of bracket orthodontics 150 m. MRR and SMRR value not showing trend of increasing or decreasing specificly. Surface characteristic after etching process disposed to make U shape which has no conical shape on the upper side feasible for injection molding but don rsquo t have spesification of optimum value contour surface roughness, so etching method has potential to be applied on mold bracket otrthodontics."

"Latar Belakang : E. faecalis merupakan bakteri yang mampu membentuk biofilm dan banyak ditemukan pada kasus kelainan periapeks. Tujuan : Mengetahui perbandingan daya antibakteri ekstrak kulit jeruk lemon (Citrus limon l.) dan klorheksidin 2% terhadap biofilm E. faecalis dari isolat klinis. Metode : Menilai kekeruhan larutan biofilm E. faecalis pasca pemaparan bahan uji, dengan ELISA reader. Hasil : Terdapat daya antibakteri ekstrak kulit jeruk lemon (Citrus limon l.) terhadap biofilm E. faecalis tetapi tidak terdapat perbedaan bermakna dengan klorheksidin 2% (p>0.05). Kesimpulan : Daya antibakteri ekstrak kulit jeruk lemon (Citrus limon l.) terhadap biofilm E. faecalis sebanding dengan klorheksidin 2%.

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ackground : E. faecalis has the ability to form biofilm and is often found in cases of periapical lesions. Aim: To compare the effectivity of lemon peel extract and 2% chlorhexidine against biofilm of E. faecalis. Method : Score the turbidity of E. faecalis biofilm after immersion in antibacterial agent, with ELISA reader. Result : Lemon peel extract has antibacterial effectivity against E. faecalis biofilm but has no significant difference compared to 2% chlorhexidine (p>0.05). Conclusion : Antibacterial effectivity of lemon peel extract against E. faecalis biofilm is equal to2% chlorhexidine. "

"Metode fitosintesis berhasil digunakan untuk pembuatan nanopartikel MoS2, NiO dan nanokomposit NiO/MoS2. Penggunaan alisin murni sebagai sumber sulfida berhasil digunakan pada sintesis MoS2. Sedangkan, penggunaan alisin yang berasal dari bawang putih membentuk MoS­2 dalam campuran dengan oksida lainnya. Di sisi lain, fitosintesis nanopartikel NiO menggunakan ekstrak daun bandotan juga berhasil dilakukan. Selanjutnya, nanokomposit NiO/MoS2 disintesis secara sonokimia menggunakan NiO-MA 800 dan MoS2 dari alisin murni. Nanokomposit yang terbentuk berukuran 60-80 nm. Nanokomposit NiO/MoS2 yang telah berhasil didispersikan pada permukaan Screen Printed Carbon Electrode (SPCE) memiliki respon arus yang paling tinggi pada elektropolimerisasi MO dibandingkan NiO dan MoS2. PMO/NiO/MoS2/SPCE diaplikasikan untuk sensor kolesterol dan menghasilkan linearitas yang baik (r2=0,9998) pada rentang konsentrasi 1-15 mg/dL, LOD 0,24 mg/dL, LOQ 0,81 mg/dL, sensitivitas 7,95x10-6 A mg-1 dL-1 cm-2, dan recovery 96,45 – 101,87%. Selain itu, uji interferensi pengukuran kolesterol terhadap 1mg/dL NaCl, CaCl2, tirosin dan glisin menunjukkan tidak adanya gangguan yang signifikan (perubahan respon arus <5%), sedangkan terhadap glukosa dan asam askorbat menunjukkan gangguan masing-masing sebesar 10,11-11,43% dan 6,93-13,36%. Pengukuran pada sampel nyata, yaitu pada susu dan yogurt menunjukkan kesesuaian dengan informasi nilai gizi yang tertera pada kemasan sebesar 95,7% dan 94,3% serta metode kromatografi gas sebesar 97,1% dan 95,2 %.

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The phyto-synthesis method was successfully used for the forming of MoS2, NiO, and NiO/MoS2 nanoparticles. The use of pure allicin as a sulfide source was successfully used in the synthesis of MoS2, while the use of allicin derived from garlic forms MoS2 in a mixture with the oxides. On the other hand, the phytosynthesis of NiO nanoparticles using bandotan leaf extract was also successful. Furthermore, NiO/MoS2 nanocomposites were synthesized sonochemically using NiO-MA 800 and MoS2 from pure allicin. The nanocomposites formed were 60-80 nm in size. NiO/MoS2 nanocomposites that have been successfully dispersed on the Screen Printed Carbon Electrode (SPCE) surface have the highest current response to MO electropolymerization compared to NiO and MoS2. PMO/NiO/ MoS2/SPCE was applied to cholesterol sensors and produced good linearity (r2 = 0.9998) in the concentration range of 1-15 mg/dL, LOD of 0.24 mg/dL, LOQ of 0.81 mg/dL, sensitivity of 7.95x10-6 A mg-1 dL-1 cm-2 and recovery 96.45 - 101.87%. In addition, the interference test of cholesterol measurements for 1mg/dL of NaCl, CaCl2, tyrosine, and glycine showed no significant disturbances (changes in current response <5%), while glucose and ascorbic acid showed a disturbance of 10.11-11.43% dan 6.93-13.36%, respectively. Measurements on real samples, namely milk and yogurt, show similarity with the nutritional value information listed on the packaging of 95.7% and 94.3% and gas chromatography methods of 97.1% and 95.2%."

"The study aimed to reveal the role of literary work, especially a novel in reflecting the social fenomena, the juvenile delinquency in the twentieth century. The data source was an English novel 'Clockwork Orange' written by Anthony Burgess. The research applied library research by using reflection theory introduced by George Lukacs. Analysis was pesented in three part, those were the identification of major character, social setting, and the reflection of juvenile delinquency. The findings were as follows, first, the major character was Alex as his high intensity in all the events that build the whole story. Second, the social setting described the life of teenagers, especially the juvenile delinquency as racial fenomena in society. Third, the role of literary work in revealing the problem above faced by the twentieth century society. Finally, it can be concluded that the literary work has played a very important role in revealing the social fenomena."

"By reading this book, business people, academics and chain practitioners have an opportunity to understand this chain. and can analyse all of its numbers and economics and exercise strategy building. This is needed since the orange juice market is a stable market in the world, growing only 1% per year, and the production costs of this chain are rising fast, due to structural changes faced by world food and agribusiness companies i.e. labour costs, energy costs, land costs, environmental costs and others. "