Kusumastuti, Hesti
Universitas Gadjah Mada

Published : 2 Documents

Found 2 Documents

Superparamagnetic Nanocomposite of Magnetite-Chitosan Using Oleic Acid as Anti Agglomeration and Glutaraldehyde as Crosslinkage Agent Suyanta, Suyanta; Sutarno, Sutarno; Nuryono, Nuryono; Rusdiarso, Bambang; Kunarti, Eko Sri; Kusumastuti, Hesti; Kurnia, Lia
Indonesian Journal of Chemistry Vol 19, No 1 (2019)
Publisher : Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (16.346 KB) | DOI: 10.22146/ijc.28989


In this research magnetite was synthesized by coprecipitation method, in which solution of NH4OH was added into the solution containing a mixture of Fe2+/Fe3+ (molar ratio 1:2) until pH 11 under strong ultrasonic agitation for 30 min. The black sediment of magnetite was filtered, washed and dried. The product was then modified by using oleic acid to prevent agglomeration. Chitosan was prepared by deacetilization of chitin, whereas chitin was extracted from shrimp shell. In the synthesis of nanocomposite, 0.5 g of chitosan and 1.5 g of oleic acid modified magnetite were introduced into 100 mL of 2% acetic acid solution, followed by sonication treatment for 10 min and magnetic stirring for 20 min. In order to perform the cross-linkage reaction, solution of 2% glutaraldehyde was added into the mixture at temperature of 40 °C for 3 h. The composite was collected by magnetic separation, followed by washing with distilled water and ethanol in a row. The product was dried and characterized by XRD, FTIR, TEM and VSM methods. The result showed that the composite had good crystal structure with a cubic inverse spinel structure, monodisperse and quasi sphere in shape with diameter of 20–25 nm. It had high saturation magnetization (43.4 emu/g) and superparamagnetic property.
Dinamika Kontrol Sosial Keluarga dan Teman Sebaya pada Remaja Berisiko Penyalahgunaan NAPZA Kusumastuti, Hesti; Hadjam, M. Noor Rochman
Gadjah Mada Journal of Psychology (GamaJoP) Vol 3, No 2 (2017)
Publisher : Fakultas Psikologi Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (508.667 KB) | DOI: 10.22146/gamajop.43439


The purpose of this research is to know in depth how the dynamics of social control family and peers on adolescents who are at risk of drug abuse. Method: This research method using qualitative research method, which uses data collecting interviews and observation. Participant: This study focused on participants who are at risk of drug abuse with the following criteria: (a) willing to be a participant, (b) gender to male or female, (c) ± adolescents aged 15-18 years, (d) adolescents who are indicated are at risk of drug abuse. Result: The results of this study indicate that adolescents who are at risk of drug abuse are smoking and drinking. High risk factors cause adolescents to be at risk for drug abuse, ie family conflicts, negative parental models, involvement of negative activities with peers, and peer-to-peer conformity. This is supported by the weakness of protection factors in adolescent behavior at risk of drug abuse. Weak family controls supported by weak peer control will increase the risk rate for adolescent drug abuse behavior. This suggests that family and peer social controls are very influential to reduce the risk of adolescent drug abusers, especially in prevention and intervention.