Judul: Karakteristik Perekat Ikan (Fish Glue) dari Kulit Ikan Patin yang Ditambahkan PVA sebagai Perekat Glulam Kayu Karet
Abstrak: Perekat ikan (fish glue) merupakan perekat dari gelatin hasil hidrolisis kolagen pada kulit ikan. Penelitian bertujuan menentukan sifat fisis dan kimia perekat dari kulit ikan patin, pengaruh penambahan polivinyl alcohol (PVA) pada perekat ikan serta sifat fisis dan mekanis glulam kayu karet (Hevea brasiliensis). Perekat ikan diperoleh dari ekstraksi kulit ikan patin pada suhu 75°C selama 10 jam yang dipekatkan. Perekat ikan diberikan perlakuan penambahan PVA sebanyak 0, 1, 2, dan 3%. Penambahan PVA berpengaruh nyata terhadap kadar padatan, viskositas dan keteguhan geser. Perekat ikan kontrol menghasilkan rendemen sebesar 49,81±6,78%, kadar padatan 36,53±3,29%, viskositas 15,25±3,42 poise, kadar abu 0,23±0,01% dan pH 5,29±0,07. Hasil tersebut memenuhi standar SNI 06- 6049-1999. Glulam kayu karet menghasilkan kerapatan sebesar 0,72±0,01 g/cm3, kadar air 11,53±0,16%, keteguhan geser 15,96±3,21 kg/cm2, kerusakan kayu 10,0±10,0%, dan delaminasi air dingin 21,23±18,53%. Kadar air glulam memenuhi standarJAS 234:2003. Parameter keteguhan geser dan delaminasi belum memenuhi standar disebabkan perekat ikan belum cukup kuat untuk merekatkan glulam kayu karet yang termasuk kedalam kayu kelas kuat II berdasarkan standar Indonesia., Fish adhesive (fish glue) is an adhesive made from gelatin hydrolyzed by collagen in fish skin. The objective of this study was to determine the physical-chemical properties of the adhesive from catfish skin, the effect of adding polivinyl alcohol (PVA) to fish glue and the mechanical-physical properties of rubber wood glulam (Hevea brasiliensis). Fish glue was obtained from the extraction of catfish skin at temperature of 75°C for 10 hours which was concentrated. Fish glue was treated with the addition of PVA as much as 0, 1, 2, and 3%. The addition of PVA significantly affected the solids content, viscosity and shear strength. Fish glue control produced yield of 49.81±6.78%, solids content 36.53±3.29%, viscosity 15.25±3.42 poise, ash content 0.23±0.01% and pH 5.29±0.07. These results are meet the standard of SNI 06-6049-1999. Rubber wood glulam resulted density of 0.72±0.01 g/cm3, moisture content 11.53±0.16%, shear strength 15.96±3.21 kg/cm2, wood failure 10.0±10.0% and cold water delamination 21.23±18.53%. The moisture content of glulam meets the JAS 234:2003 standard. The parameters of shear strength and delamination don’t meet the standard because the fish glue is not strong enough to bond rubber wood glulam which is classified as strength class II regarding to Indonesian standard.
Keyword: fish glue, glulam, PVA

Judul: Characteristics of Fish Glue Catfish Skin
Abstrak: Lem ikan atau fish glue merupakan polimer alami yang dapat digunakan sebagai perekat. Fish glue memiliki kelemahan, yaitu adanya kontaminasi mikroorganisme selama masa penyimpanan terutama kontaminasi jamur. Agen antimikroba atau pengawet dapat menjadikan fish glue menjadi lebih lama dalam penyimpanan. Penelitian ini bertujuan untuk mengevaluasi pengaruh penambahan pengawet boraks dengan konsentrasi yang berbeda terhadap karakteristik fish glue berbahan kulit ikan patin dan efektivitasnya terhadap pertumbuhan mikroba. Boraks ditambahkan ke dalam fish glue dengan konsentrasi 0,3%; 0,7% dan 1% (perbandingan boraks dan fish glue) serta kontrol. Tahapan penelitian terdiri dari preparasi kulit ikan patin, ekstraksi, produksi fish glue, pengujian karakteristik kimia dan fisik fish glue, kemampuan pertumbuhan mikroorganisme selama 10 hari dan pengamatan mikroskop. Hasil penelitian menunjukkan, bahwa penambahan boraks berpengaruh terhadap karakteristik kimianya, dan tidak berpengaruh terhadap karakteristik fisiknya. Kemunculan mikroorganisme tercepat yaitu pada hari ke-3 dengan perlakuan kontrol dan kemunculan mikroorganisme terlambat yaitu hingga hari ke-10 tidak ada tanda kemunculannya pada perlakuan 1% boraks., Fish glue is a natural polymer that can be used as an adhesive. Fish glue has a weakness, namely the presence of microorganism contamination during the storage period, especially fungal contamination. Antimicrobial agents or preservatives can make fish glue last longer in storage. This study aims to evaluate the effect of adding borax preservatives with different concentrations on the characteristics of fish glue made from catfish skin and its effectiveness on microbial growth. Borax was added to fish glue with a concentration of 0.3%; 0.7% and 1% (comparison of borax and fish glue) and controls. The research stages consisted of preparation of catfish skin, extraction, production of fish glue, testing of the chemical and physical characteristics of fish glue, the ability to grow microorganisms for 10 days and microscopic observation. The results showed that the addition of borax had an effect on its chemical characteristics, and had no effect on its physical characteristics. The fastest emergence of microorganisms was on the 3rd day with control treatment and the late appearance of microorganisms was until the 10th day there was no sign of their appearance in the 1% borax treatment.
Keyword: fish glue, gelatin, kapang, pengawet, stratum compactum

Judul: Bifurkasi Hopf pada Model Siklus Bisnis Kaldor Kalecki tanpa dan dengan Waktu Tunda
Abstrak: Business cycle model is one of dynamical system models in economic. One of the business cycles model is Kaldor-Kalecki model. Kaldor-Kalecki business cycle model that is written in delayed defferential equations, is a business cycle model that involves gross product and capital stock of a company. In this paper Kaldor-Kalecki business cycle model is analyzed using both nondelay and delay in time of capital stock. By Taylor expansion for the time delayed model, an analysis of stability around the fixed points has been done. Furthermore, by using Hopf bifurcation theorem, it can be shown that there exists periodic orbits and limit cycle. In the nondelayed model, changing the parameter of goods market could lead to the occurrence of Hopf bifurcation and the existence of limit cycle. Similarly, for the delayed model, it has been shown that changing the time delay parameter may result in the occurrence of Hopf bifurcation and limit cycle.
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