Hydroxyapatite (HAp) has been used for various applications such as orthopedics, drug delivery material, and bone tissue engineering. It is well known that HAp has a good biocompatibility and osteoconductivity, so HAp can be used in biomedical applications. Hydroxyapatite can be combined with other materials, in particular polymer, to expand its range of applications. In this study, the polymer that will be used as a support for the HAp composite is alginate (Alg). The HAp/Alg composite has been synthesized by the precipitation method. The XRD results show that the crystal system of HAp was hexagonal. The spheric-like shaped particles can be observed from SEM images, and particle size distribution spread from 400 to 1100 nm. The EDS spectrum exhibited the peak of Ca, C, P, and O elements, indicating that alginate had interacted with hydroxyapatite in the synthesized composite. The as-fabricated composite showed not only good crystallinity but also high thermal resistance. Thermogravimetric-differential thermal analysis (TGA-DTA) revealed that the HAp/Alg composites have a constant weight at 750 °C, so it might be applied in advanced applications such as bioimaging, drug carrier, and other cancer treatments.

Karbon aktif dari cangkang kelapa sawit sebagai bahan elektroda superkapasitor telah diteliti. Superkapasitor dirangkai dengan metoda plat/sandwich yang dipisahkan oleh separator. Untuk mendapatkan nilai kapasitansi yang besar dilakukan variasi jumlah aktivator terhadap karbon menggunakan aktivator KOH. Sifat fisikokimia dari karbon aktif diteliti dengan melakukan karakterisasi menggunakan XRD (X-Ray Diffraction), SEM-EDX (Scanning Electron Microscopy-Energy Dispersive X-Ray) dan SAA (Surface Area Analyzer) dan sifat elektrokimianya diteliti dengan pengukuran CV (Cyclic Voltammetry). Karbon aktif dengan perbandingan 1:5 memiliki luas permukaan yang paling besar yaitu 793,326 m2/g dan nilai kapasitansi spesifik tertinggi yaitu 99,151 F/g. The activated carbon from oil palm kernel shell as an electrode material for supercapacitors has been investigated. The supercapasitor was assembled by plate/sandwich methods. Both electrodes were separated by using a separator. To increase the capacitancy value, variations in the number of activators on carbon were carried out using KOH activator. The physicochemical properties of activated carbon were investigated by characterizing using XRD (X-Ray Diffraction), SEM-EDX (Scanning Electron Microscopy-Energy Dispersive X-Ray) and SAA (Surface Area Analyzer) and the electrochemical properties were investigated by measuring CV (Cyclic Voltammetry). Activated carbon with a ratio of 1:5 has the largest surface area of 793,326 m2/g and the highest specific capacitance value is 99,151 F/g.Keywords: activated carbon, supercapasitor, activator, surface area, specific capacitance

This research is intended to learn inhibition efficiency of mild steel corrosion in peat water using two type of chitosan. First chitosan is without treatment and the second one is synthesized by ionotropic gelation method and then is characterized by Fourier transform Infrared spectroscopy (FT-IR) and Scanning Electron Microscopy (SEM). Diameter of chitosan porous is about 500 nm which is measured based on morphological photo using SEM with inhomogeneous porous shape and porous distribution is unsmooth . Effect of chitin and chitosan on the corrosion of mild steel in peat water is studied using weight loss method. It is found that corrosion inhibition efficiency depends on peat water pH, inhibition technique and interaction time. The results show that inhibition efficiency of chitosan without treatment and with treatment are 88.73% and 93.32% respectively. The inhibition is assumed to occur via physicsorption of the chitin and chitosan molecules on the metal surface. The Langmuir adsorption isotherm is tested for their fit to the experimental data.

Studi awal tanin dari kulit kayu A.auriculiformis …….. (Mutiar et al.) 41 Majalah Kulit, Karet, dan Plastik, 34(2), 41-48, 2018 ©Author(s), https://doi.org/10. 20543/mkkp.v34i2.3967 Studi awal tanin dari kulit kayu Acacia auriculiformis A. Cunn. ex Benth. dari hutan tanaman industri untuk bahan penyamak kulit ABSTRACT This study aims to determine the tannin content and extraction method of the content and levels of tannin from the bark of Acacia auriculiformis A. Cunn. ex Benth. The bark is obtained from PT. Arara Abadi. The extract methods are water bath, ultrasonic bath, autoclave, reflux, and microwave. The tannin extract produced was applied as a vegetable tanning agent. The extract which is the best yield of the method used. The results showed that the highest yield was obtained by the autoclave method which was 29.65%. The results of chemical analysis of the extract produced were 52.79% tannin content, 62.40% water soluble materials. Application of the tannin extract as a vegetable tanning agent on goat skin was carried out chemical analysis, observation of physical and organoleptic properties. The quality of tanned skin was seen from the chemical properties, i.e. water content of 15.02%, 3.20% fat content, 3.44% ash content, 3.57% water soluble substances, 43.79% raw skin substances, 30.98% bonded tannins, 70.74% degree of tannage. Observation of physical properties of tanned skin were tensile strength 254.21 kg/cm 2 , 63.95% elongation at break, 9.27 mm zwik resistance/crack (non-broken nerf), thickness 0.9 mm, and brown color. A. auriculiformis bark extract contains tannins and potential as tanning agent. ABSTRAKPenelitian ini bertujuan untuk mengetahui kandungan tanin dan metode ekstraksi terhadap karakteristik dan kadar tanin dari kulit kayu Acacia auriculiformis A. Cunn. ex Benth. Kulit kayu diperoleh dari HTI PT. Arara Abadi. Metode ekstrak yang digunakan water bath, ultrasonic bath, autoclave, refluks dan microwave. Ekstrak tanin yang dihasilkan diaplikasikan sebagai bahan penyamak nabati. Ekstrak yang digunakan adalah rendemen tertinggi dari metode yang digunakan. Hasil penelitian menunjukkan bahwa rendemen tertinggi diperoleh dengan metode autoclave yaitu 29,65%. Hasil analisis kimia dari ekstrak yang dihasilkan kadar tanin adalah 52,79%, bahan larut air 62,40%. Aplikasi ekstrak tanin sebagai bahan penyamak nabati menggunakan kulit kambing dilakukan analisis kimia, pengamatan sifat fisik dan organoleptis. Kualitas kulit tersamak ditinjau dari sifat kimia diantaranya kadar air 15,02%, kadar lemak 3,20%, kadar abu 3,44%, kadar zat larut air 3,57%, kadar zat kulit mentah 43,79%, kadar tanin terikat 30,98% dan derajat penyamakan 70,74%. Pengamatan sifat fisik kulit tersamak yaitu kekuatan tarik 254,21 kg/cm 2 , kemuluran 63,95%, ketahanan zwik/keretakan 9,27 mm (nerf tidak pecah), ketebalan 0,9 mm, warna coklat. Ekstrak kulit kayu A. auriculiformis mengandung tanin dan berpotensi untuk digunakan sebagai bahan penyamak kulit.

Studi komputasi pada struktur, sifat antioksidan dari scopoletin dan turunannya telah dipelajari melalui analisis DFT/B3LYP/6-31G dalam fase gas. Analisis toksisitas dengan OSIRIS Property Explorer online telah menunjukkan bahwa scopoletin dan turunannya tidak bersifat mutagenik, tidak menyebabkan tumor dan iritasi, akan tetapi beberapa diantaranya memiliki resiko tinggi terhadap sistem reproduksi. Scopoletin dan turunannya memiliki skor obat berkisar antara 0,270 - 0,503 yang menunjukkan bahwa senyawa tersebut memiliki kemiripan obat yang sebanding dengan obat yang ada. Sifat antioksidan scopoletin dan turunannya dapat dijelaskan dengan baik oleh mekanisme transfer atom hidrogen (TAH) dengan nilai BDE berkisar antara 69,986 - 90,510 Kkal/mol dalam fase gas. Nilai BDE sangat dipengaruhi oleh sifat substituen dan ditemukan bahwa substituen pendorong elektron menurunkan nilai BDE. Nilai BDE menurun dengan urutan dari senyawa 9>6>7>8> scopoletin >1>10>3>5>4>2 dalam fase gas, sehingga urutan kemampuan mendonasikan atom hidrogen adalah 2>4>5>3>10>1> scopoletin >8>7>6 >9. Nilai ΔBDE dari scopoletin dan turunannya pada fase gas berkisar dari -16,064 hingga 4,460 Kkal/mol. Nilai BDE fase gas yang dihitung secara signifikan lebih rendah daripada nilai SET-PT dan PA pada fase gas. Hasil ini lebih lanjut menunjukkan bahwa TAH secara termodinamika lebih disukai daripada SET-PT, PA dan ETE dalam fase gas.   

Rutin flavonoid compounds have been isolated from cassava leaves and tested for their corrosion resistance against mild steel. Inhibition efficiency and adsorption properties were studied using the weight loss method at temperature variations of 303K, 313K, 323K and 333K and concentration variations of 0.1; 0.5; 1.0; 5.0; and 10 g/L. Potentiodynamic polarization was used to determine the inhibitor type of Cassava Leaf Routine (RCL). The results showed that RCL can reduce the corrosion rate and increase the corrosion inhibition efficiency of mild steel. The thermodynamic parameters have been calculated and the result is that the adsorption corrosion mechanism by physisorption takes place spontaneously with increasing temperature. Based on potentiodynamic polarization, the efficiency of corrosion inhibition by RCL with a concentration of 10 g//L on mild steel was 81.58%. RCL as a mixed corrosion inhibitor.

Carboxymethyl chitosan (CMC) was synthesized with different methods by reacting chitosan with monochloroaceticacid in the presence of sodium hydroxide under variation conditions. The above samples were characterized byFourier transform infrared spectroscopy (FTIR) and soluble in water in range of pH. The CMc were soluble in watera wide range of pH and applied as corrosion inhibitor for steel in water. The inhibiting influence of CMC was studiedby potentiodynamic polarization method. It was found thad corrosion rate was dependent on water pH and CMCconcentration. The results show that optimum the inhibition efficiency at pH 5 and 1 ppm concentration CMC, i.e.,77%. The adsorption of used compound on the steel surface obeys modified Langmuir isotherm. Polarizationmeasurement show that the CMC acts essentially as a anodic-type inhibitor.

Background: Inflammation is a protective mechanism of the immune system due to tissue damage caused by infectious and non infectious agents. The most widely used synthetic drugs in treating the inflammation is NSAIDs (Non Steroidal Anti Inflammatory Drugs) but long-term use of NSAIDs can cause undesirable side effects. Tempeh (R. oligosporus) is one of the processed soy products that is made through the fermentation process by Rhizopus sp. Tempeh has many benefits for health, one of which is anti-inflammatory. According to some research results, tempeh is recognized as having an anti-inflammatory role. The mechanism of tempeh as an anti-inflammatory, namely by maintain a balance between reactive oxygen species (ROS) and antioxidants in the body, increasing the production of anti-inflammatory cytokines (IL-10), suppressing the activation of NF-kB. This process can suppress the expression of iNOS and COX-2 and inhibit several inflammatory mediators, such as TNF-α, IL-1β and NO. Objective: The purpose of this study was to investigate anti-inflammatory activity of soybean tempeh (R.oligosporus) and find out the potential of active compounds in soybean tempeh that play role as anti-inflammatory. Method: The study was conducted by collecting and examining of various literatures on potential of soybean tempeh (R.oligosporus) in suppressing inflammatory response. Conclusion: The active compounds found in soybean tempeh (R. oligosporus) is able to suppress the inflammatory response.