Judul: Sifat Pulp Campuran antara Pulp Asli Bambu dan Pulp Karton Bekas (Old Corrugated Containers)
Abstrak: OCC was soaked for 7 days and disintegrated afterward. Soda pulping of bamboo was carried out following the pulping parameters of 35% NaOH charge, L/W of 4/1, maximum temperature of 170 oC and total cooking time of 3 hours. Kappa number and pulping yield were determined based on TAPPI T236 cm-85 standard. Bamboo and OCC pulp was bleached following the method of D0ED1D2. Bleached bamboo pulp was beaten up to the freeness of 100, 200, 300, and 400 ml CSF. While that of OCC was up to 400 ml CSF only. The composisitions of bamboo/OCCpulp mixture (B/K) were 0/100, 20/80, 40/60, 60/40, 80/20 and 100/0. Physical and optical properties of pulp mixture were determined based on TAPPI T205 sp-02 standard. The pulp composition of (B/K) 20/80 at freeness level of 400 ml CSF was resulted in the highest strength properties based on Duncan scoring. Pulp beating was able to decrease the composition of bamboo pulp in pulp mixture while retaining the strength properties
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Judul: Sifat optik dan mekanik pulp karton bekas bersubstitusi pulp asli bambu
Abstrak: Kertas bekas adalah sumber serat potensial untuk dimanfaatkan. Pemanfaatan kertas bekas ini menguntungkan dari segi ekonomi dan berdampak positif bagi lingkungan. Secondary pulp dari kertas karton yang didominasi pulp serat pendek akan menghasilkan mutu sifat mekanik lebih rendah jika dijadikan lembaran pulp baru (Minor dan Atalla, 1992). Substitusi pulp serat pendek kertas karton pada kadar tertentu dengan serat panjang bambu keinungkinan dapat meningkatkan sifat mekanik lembaran pulp yang baru. Jenis bambu yang digunakan adalah bambu tali (Gigantochloa aptis) dengan umur 2 tahun. Taraf perlakuan yang diberikan pada substitusi pulp ini adalah komposisi pulp karton loo%, bambu loo%, bambu : karton = 70 : 30, bambu : karton = 60 : 40, bambu : karton = 50 : 50, bambu : karton = 40 : 60, dan bambu : karton = 30 : 70. Sebelum dilakukan analisa terhadap sifat fisik dan sifat optik, pulp masing-masing perlakuan diputihkan dengan menggunakan tahapan bleaching DEDP. Berdasarkan hasil skoring Duncan, lembaran pulp dengan komposisi bambu : karton = 70 : 30 inerupakan lembaran pulp dengan sifat fisik dan optik yang terbaik dengan nilai indeks tarik, indeks sobek, indeks retak dan derajat putih berturut-turut adalah 27.66 Nmlg, 7.00 N.m2/kg, 1.27 kPa.m2/g dan 72.64%. Sifat mekanik dan optik yang dihasilkan tersebut menunjukkan peningkatan yang signifikan bila dibandingkan dengan kontrol yaitu lembaran pulp dengan komposisi karton 100%. Pulp asli bambu lebih berperan dalam menentukan sifat-sifat pulp yang memerlukan panjang serat tinggi seperti kekuatan sobek, sedangkan pulp daur ulang lebih berperan dalam menentukan sifat-sifat kekuatan pulp yang memerlukan ikatan antar serat yang baik.
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Judul: Pengaruh vaksinasi terhadap dinamika populasi pada model SIR (Susceptible-Infected-Recovered)
Abstrak: SIR model can be used to model the spread of diseases in a closed population based on certain assumptions. In this research, the SIR model is formulated by including the factor of vaccination. As the result, the model has been shown to have two equilibrium points, i.e. disease free and endemic equilibrium. A simulation study is carried out to illustrate the model. The results show that some equilibrium points are asymptotically stable. Moreover, a minimum level of vaccination has been defined. For the vaccination level less than the minimum level, increase in the vaccination level results in decrease of the proportion of infected individuals in the corresponding equilibrium point. On the other hand, for the vaccination level greater than the minimum level, increase in the vaccination level results in decrease the proportion of susceptible individuals in the corresponding equilibrium point. Furthermore, when vaccination level is greater than the minimum level, it is found that the time needed for the disease to extinct is shorter.
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