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"Latar belakang: Plasmodium falciparum merupakan salah satu parasit penyebab penyakit malaria yang menyerang manusia. Mitokondria P. falciparum memiliki perbedaan komponen dengan manusia terutama jenis enzim yang terlibat dalam rantai transpor elektron. Malat: kinon oksidoreduktase MQO adalah enzim fungsional yang bekerja dalam mengkatalisis konversi malat menjadi oksaloasetat yang dibutuhkan pada siklus asam sitrat. Elektron yang dihasilkan akan dimanfaatkan untuk pembentukan ATP melalui fosforilasi oksidatif. a-mangostin merupakan senyawa xanton utama yang berasal dari manggis, Garcinia mangostana Linn. Ekstrak kulit buah manggis dan a-mangostin diketahui memiliki efek antiplasmodium yang dibuktikan melalui penelitian in vitro.Metode: Enzim rekombinan PfMQO diekspresikan pada bakteri Eschericia coli BL21star DE3 . Fraksi membran E.coli yang mengikat enzim diisolasi menggunakan sentrifugasi kecepatan 104.000xg. Karakteristik enzim PfMQO ditentukan secara spektrofotometri dengan mengikuti kinetika reaksi enzim terhadap substrat malat dan ubikinon pada 600 nm. Aktivitas penghambatan ?-mangostin terhadap PfMQO diuji dengan mengikuti reduksi ubikinon pada panjang gelombang 278 nm. Uji konfirmasi aktivitas inhibisi ?-mangostin dilakukan terhadap kultur P. falciparum in vitro dan sel limfosit manusia.Hasil: PfMQO bekerja pada kondisi optimal di suhu 37 C dan pH netral. Enzim PfMQO yang terikat pada fraksi membran bakteri memiliki karakter nilai aktivitas spesifik sebesar 13,3890 ?mol/menit/mg, konstanta Michaelis-Menten Km untuk ubikinon sebesar 6,2090 0,6486 ?M dan Vmax sebesar 16,9600 0,5866 ?mol/menit/mg . Nilai konstanta Michaelis-Menten Km untuk malat sebesar 5,9960 0,3440 mM dan Vmax sebesar 16,4000 0,3838 ?mol/menit/mg . a-mangostin memiliki aktivitas penghambatan terhadap enzim PfMQO dengan nilai IC50 sebesar 1,7390 0,0077 M. Penghambatan a-mangostin terhadap enzim PfMQO di situs pengikatan malat dan ubikinon melalui mekanisme campuran dengan nilai konstanta inhibisi Ki masing-masing sebesar 2,3260 mM dan 1,6720 ?M. a-mangostin memiliki aktivitas penghambatan pertumbuhan terhadap kultur P. falciparum IC50 = 5,7060 1,0976 M . Uji toksisitas a-mangostin terhadap sel limfosit manusia memberikan nilai hambatan CC50 sebesar 11,3800 ?M. Evaluasi toksisitas ?-mangostin melalui nilai perhitungan SI didapatkan SI terhadap PfMQO sebesar 6,5440 dan kultur P. falciparum 1,9944.Kesimpulan: Enzim MQO dalam tubuh parasit P. falciparum dapat ditetapkan sebagai target pengobatan malaria dan a-mangostin berpotensi untuk dikembangkan sebagai antimalaria namun masih bersifat toksik bagi sel manusia.

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Background Plasmodium falciparum is one of parasite causing malaria disease that attacks human. Mitochondria of P. falciparum has a different component with human especially enzyme that involve in electron transport chain. Malate quinone oxidoreductase MQO is functional enzyme which catalyze conversion of malate to oxaloacetate which needed in citric acid cycle. Generated electron will be utilized to form ATP through oxidative phosphorylation. a mangostin is a main xanton of mangosteen, Garcinia mangostana Linn. Mangosteen pericarp extract and a mangostin have been known in having antiplasmodial effect by in vitro study.Method PfMQO recombinant enzyme was expressed in bacteria Eschericia coli BL21star DE3 . E.coli membrane fraction that expressed enzyme were isolated using centrifugation 104.000 x g. Characterization of PfMQO were determined by spectrophotometry with following kinetic reaction of enzyme to malate and ubiquinone as substrate at 600 nm. Inhibition activity mangostin against PfMQO were assayed by following ubiquinone reduction at 278 nm. Confirmation test of mangostin inhibition activity were conducted againts Plasmodium falciparum culture in vitro and human lymphocyte cell.Results PfMQO has an optimum condition at 37 C and netural pH. PfMQO enzyme which bind on bacterial membrane fraction has a specific activity 13.3890 mol minutes mg, Michaelis Menten value Km for ubiquinone is 6.2090 0.6486 M and Vmax is 16.9600 0.5866 mol minutes mg . Michaelis Menten value Km for malate is 5.9960 0.3440 mM and Vmax is 16.4000 0.3838 mol minutes mg . mangostin has inhibition activity against PfMQO enzyme with inhibition concentration IC50 value of 1.7390 0.0077 M. Inhibition of mangostin to PfMQO at malate and ubiquinone binding site by mixed type inhibition with inhibition constant Ki values are 2.3260 mM and 1.6720 M, respectively. mangostin has inhibition activity to P. falciparum growth with IC50 value of 5.7060 1.0976 M. Toxicity value CC50 to human lymphocyte cells is 11.3800 M. Evaluation of mangostin toxicity based on SI with SI value to PfMQO of 6,5440 and to P. falciparum culture of 1,9944.Conclusion PfMQO enzyme in parasite P. falciparum body could be determined as malaria drug target and a mangostin is potential to be developed as antimalarial agent but still toxic for human cell. "

"Pelapisan dengan tungsten karbida banyak digunakan sebagai bahan pelapis memberikan kombinasi sifat mekanik ketangguhan tinggi, kekerasan tinggi, dan kekuatan yang baik. Pada penelitian ini 0,05 wt dan 0,15 wt MWCNT dicampur dengan proses ball milling pada larutan etanol dengan material serbuk WC Tungtec 10112. Sebelum pencampuran dengan WC Tungtec 10112 dilakukan, dispersi dan deagglomerasi dari MWCNT dilakukan melalui metode ultrasonikasi dengan larutan SDS. Hasil pencampuran serbuk nanokomposit selanjutnya dilakukan penyemprotan logam nyala api oksi asetilen pada sebuah substrat baja perkakas. Mikrostruktur dari lapisan yang Diamati dengan menggunakan scanning electron microscope SEM , energy dispersive X-ray spectroscopy EDS , dan X-ray diffraction XRD digunakan untuk mengamati senyawa yang terbentuk. Kekerasan mikro diukur dengan metode mikrovickers dan ketahanan aus abrasif diuji dengan menggunakan mesin ogoshi berdasarkan standar ASTM E384. Hasil eksperimen menunjukkan bahwa proses dispersi dengan ultrasonikasi menggunakan larutan SDS dan pencampuran dengan balll-milling baik digunakan untuk proses dispersi CNT dengan matriks Tungtec 10112 karena menghasilkan dispersi dan ditribusi yang baik antara CNT dan serbuk Tungtec 10112 sehingga mampu meningkatkan nilai kekerasan dan ketahanan aus lapisan. Penambahan sebanyak 0,15 wt CNT Menunjukkan Kenaikan ketahanan aus hingga 50 Dibandingkan dengan pelapisan WC tanpa penguat CNT. Kekerasan lapisan dengan penguat CNT juga Meningkat Dibandingkan dengan lapisan WC tanpa penguat dan substrat dengan nilai kekerasan sebesar 1717 HV. Hasil pelapisan dengan penambahan penguat CNT Menunjukkan ketahanan aus abrasif tinggi daripada lapisan tanpa penguat CNT menyimpulkan bahwa CNT dapat menjadi alternatif yang baik untuk meningkatkan ketahanan aus abrasif lapisan.

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WC is widely used as a tribological coating material providing a combination of high toughness, high hardness, and good strength. In this work, 0.05 wt. 0,15 wt of CNTs were mixed by ball milling in ethanol solution with WC Tungtec 10112 powders. Before mixing with WC Tungtec 10112, dispersion is done through ultrasonication method with SDS solution. The mixture was thermally sprayed using the flame spraying process onto a plain tool steel substrate. The microstructures of the coatings were characterized using scanning electron microscope SEM , energy dispersive X ray spectroscopy EDS, and X ray diffraction XRD were used for phase identification. The microhardness was measured by Vickers indentation and the abrasive wear resistance was evaluated using ogoshi machine according to ASTM E384 standard. Effects of CNTs on the microstructure, abrasion wear and microhardness of the coatings were investigated.

Experimental results have shown ultrasonication using SDS solution and ball milling was suitable to disperse CNTs with WC Tungtec 10112 feed powders since it produces an adequate relationship between CNTs 39 and WC Tungtec 10112 which enhances the microhardness and wear resistance of coatings. The 0,15 wt CNT WC coating showed an increase in wear resistance of almost 50 compared with WC coating without CNT reinforced,The hardness of coating reinforced CNT is increased compared to the WC coating and substrate with the value of 1717 HV. All reinforced coatings showed a higher abrasive wear resistance than non reinforced indicating that CNTs are a good alternative to improve abrasion wear resistance of WC coatings."

"In the past couple of years, several studies have demonstrated that T- helper cells play an important role in the induction and reaction process of allergy. The T-helper cell (T-h) is a kind of T lymphocyte. At first, in the year 1921 Praustniz and Kustner, as quoted by Romagnani, stated the concept that allergy is an interaction between allergens and the IgE (Immunoglobulin E) specific antibody that is attached to IgE receptors on mast cells or mastocytes, which would then release its mediators. Other factors that also play a role in the development of allergy is lymphokine, produced by T-cells, which regulate IgE antibody production by the B-cell.1 Lymphokine or cytokine is a hormone-like substance released by T-cells, B-cells, or other cells, that function as intercellular signaling substances in the regulation of immune responses towards outside stimuli.'"

"KOMPARASI SIFAT KIMIA DAN FISIK SERBUK UO2 HASIL KONVERSI YELLOW CAKE LIMBAH PUPUK FOSFAT DAN YELLOW CAKE KOMERSIAL MELALUI JALUR ADU. Serbuk UO2 adalah bahan baku pembuatan bahan bakar reaktor nuklir yang didapatkan dari hasil konversi yellow cake. Sumber yellow cake umumnya berasal dari bahan mineral uranium. Uranium juga banyak terdapat pada limbah pabrik pupuk fosfat. Dengan demikian pemanfaatan limbah pabrik pupuk fosfat dapat menyelesaikan dua masalah yaitu pencemaran lingkungan dan ketersediaan bahan baku bahan bakar nuklir. Tujuan penelitian adalah mendapatkan serbuk UO2berderajat nuklir dari yellow cake limbah pabrik pupuk fosfat dan untuk mengetahui kualitasnya maka hasil penelitian ini di komparasi dengan yellow cake komersial. Telah dilakukan kegiatan konversi yellow cake via jalur Amonium Diuranat (ADU) terhadap yellow cake yang berasal dari limbah pabrik pupuk fosfat (A) dengan pembanding yellow cake komersial (B). Serbuk UO­2 yang dihasilkan melalui konversi jalur ADU dikarakterisasi sifat kimia dan fisiknya. Hasil percobaan menunjukkan bahwa yellow cake yang berasal dari limbah pabrik pupuk fosfat sangat potensial menjadi bahan baku pembuatan serbuk UO2 berderajat nuklir, meskipun masih perlu dilakukan perlakuan khusus untuk meningkatkan kemurniannya."

"The important thing considered in the processing of fish mince meat based products is gel forming ability, which is affected by additives applied in the processing of the products. This research was aimed at studying the effect of TGase and salt addition on the physical and sensory properties of restructured product from Priacanthus macracanthus. Salt was added into minced meat at the concentration of 0, 1 and 2%, TGase with the concentration of 0; 0.3; 0.6 and 1%. The meat dough was then filled into plastic tubes and heated at 30oC for an hour before being heated at 90oC. The restructured meat was then evaluated its sensory properties texture profile (hardness,chewiness, gumminess, cohesiveness, springiness and breaking force, deformation/distance, gel strength), and its microscopic observation under the scanning electron microscope. The result showed that addition of salt as well as TGase gave significant effect on the sensory properties related to texture, appearance and brightness; and physical properties ofthe restructured products espescially gumminess and breaking force. Based on the sensory score, addition of 2% salt wasenough to produce gel which met with panelist preference, however based on the physical/texture properties addition of 2% salt and 0.3% TGase was needed to increase the gel properties. At this treatment combination, the gel strength produced was 3,235 g cm."