Judul: Penyusunan persamaan penduga volume pohon kelompok jenis Dipterocarpaceae di PT Timberdana Kalimantan Timur
Abstrak: Tree volume estimation especially standing tree, still a practical problem for the forester. Tree volume table is a common way to describe the relation between tree volume and its estimation variables (tree diameter or height). Berkhout model (V = aDb ; where : V = volume, D = diameter breast height, a dan b = constans) is a simple tree volume estimator because only use single variable which is tree diameter (D). It is one of many models with clear thought structure, mathematically derivated from cylinder volume using form factor (Suhendang 1993). Berkhout model is a non linear model which usually it should be transformed to linear model using logaritmic transformation to find regression constans. Statistical softwares development today, made that’s a problem no more. This research aims (1) to find better accuracy for tree volume estimation using Berkhout model, by transformation or without transformation; and (2) to find the best tree volume model for dipterocarpacea in PT Timberdana Kalimantan Timur. Data used in this research consist of 96 tree samples of dipterocarpaceae in PT Timberdana, East Kalimantan. Data divided into two data sets for model building (63 tree) and validation (33 tree). Data used in this research gives that Berkhout model equation built using transformation to linear model (V = 0.000411D2.214) has a better accuracy than model without transformation. The best tree volume equation of dipterocarpaceae in PT Timberdana is exponential association model, expressed by the equation : V = -3.920*(1.386  e-0.0142D), while Berkhout model is in second place together with quadratic fit and sinusoidal fit models.
Keyword: 

Judul: Penyusunan model penduga volume pohon jenis Keruing (Dipterocarpus sp.) di IUPHHK-HA PT. Salaki Summa Sejahtera, Pulau Siberut, Sumatera Barat
Abstrak: A careful, rational and directional forest planning should be conducted to achieve sustainable forest management. Periodic Census Inventory of Forest/Inventarisasi Hutan Menyeluruh Berkala (IHMB) is important to arrange ten years of Work Planning on Timber Utilization/Rencana Kerja Usaha Pemanfaatan Hasil Hutan Kayu (RKUPHHK). Providing aid of inventory is one of important things to support IHMB and reduce error in measurement. One of the methods to estimate trees’ volume is by using table of volume. The table of volume is useful to estimate volume of certain trees in a stand forest then to estimate their standing stock. The aims of this research are to arrange and obtain equality model of trees’ volume estimation from species of Dipterocarpus sp. In this research, the trees were selected purposively by diameter consideration, those which have normal growth and representative diameter. The total of samples was 55 trees; 45 trees were for model construction and 10 trees for validation purpose those trees were determined randomly. Data was analyzed using the least square method and the estimation of trees volume was based on measurement parameters of standing trees and felled trees. Based on regression analysis, the appropriate equality model to estimate volume of Dipterocarpus sp. with bark is V = 0,00014 D2,49 (R2 = 98,00%, s = 0,08). This model is proposed to estimate volume of Dipterocarpus sp. in order to support forest planning in PT. Salaki Summa Sejahtera, West Sumatera.
Keyword: 

Judul: Durability of Specific Immunoglobulin (Ig) Y Againts Influenza and Covid-19 in Sunscreen
Abstrak: The benefit of specific immunoglobulin Y (Ig Y) as an active ingredient in personal care products such as sunscreen has not been properly studied. Our study aims to evaluate the reliability of specific IgY against influenza and the COVID-19 virus in a sample sunscreen product. Specific IgY influenza and COVID-19 viruses were inserted in the sample sunscreen at two concentrations of 0.1% and 0.25%. Three treatments were observed: control (C) sunscreen without IgY, treatment 1 (T1) sunscreen with 0.1% IgY, and treatment 2 (T2) sunscreen with 0.25% IgY. Organoleptic observations were carried out to monitor changes in aroma, color, and texture, and sunscreen sampling was done every week for 6 weeks. The durability of IgY was evaluated using an enzyme-linked immunosorbent assay (ELISA) and a neutralization assay. Organoleptic observation from weeks 1 to 6 showed consistency in its aroma, color, and texture. Enzyme-linked immunosorbent assay and neutralization assay (NA) results of the T1 and T2 groups showed negative results except for sample T1 at week 5, which showed a positive result in the Influenza A ELISA. Based on the results, it seems that IgY concentrations of 0.1% or 0.25% were not optimal. However, this negative result might be due to low concentration of the IgY and the presence of beeswax, which inhibits IgY and causes it to dissolve in distilled water, thus preventing it from being detected in the assay.
Keyword: Immunoglobulin Y, Sunscreen, Influenza, COVID-19, Biological Activity