The objective of this study was to determine the effect of chemical treatment on the coconut fiber surface morphology. This study is divided into three stages, preparation of materials, treatment and testing of coconut fiber. The first treatment is coconut fiber soaked in a solution of NaOH for 3 hours with concentration, respectively 5%, 10%, 15%, and 20%. The second treatment is coconut fiber soaked in KMnO 4 solution with a concentration of 0.25%, 0.5%, 0.75%, and 1% for 3 hours. The third treatment is coconut fiber is soaked in H 2 O 2 solution with a concentration of 5%, 10%, 15%, and 20% for 3 hours. At each treatment the fiber is dried in an oven at a temperature of 90 o C for 5 hours. Coconut fibers that had been the first, second, and third treated, sorted out for chemical composition, single fiber tensile and SEM testing. Tensile strength of single coconut fiber was tested following ASTM 3379-02 by using a tensile testing LR10K Plus 10 kN Universal Materials Testing Machine. The fiber surface morphology was examined using electron microscopy Vega3 Tescan Scanning Electron Microscope (SEM) at 5kV voltage, and X-ray diffraction, 30 kV, 15 mA, at scan speed 2.000 deg./min . The result shows that the highest tensile strength of the fiber obtained in the first treatment namely N4. In general the mechanical strength of the fiber decrease slightly however, the fiber surface morphology becomes rough. NaOH treatments cause crystallization on the surface of the fiber. Crystallinity index was decreased with increasing concentration of NaOH. The second treatment caused the trench grooves on the surface of the fiber that can improve bonding between fiber and matrix.

Artikel ini berjudul Historical Thinking Model In Achieving Cognitive Dimension Of Indonesian History Learning. Artikel ini di tulis oleh Mohamad Zaenal Arifin Anis, Herry Porda Nugroho Putro, Heri Susanto, Kurnia Puji Hastuti, dan Mutiani. Artikel ini membahas model berpikir historis dengan tujuan untuk mengembangkan model evaluasi pemikiran sejarah pada mahasiswa tingkat perguruan tinggi dan dengan adanya penelitian ini diharapkan menjadi instrument evaluasi pemikiran sejarah yang di ujikan dan pemenuhan unsur pedagogis

Abstract—The goals of this study was to determine the effect of alkali concentration in the soaking coconut coir fiber (S2K) to changes in coconut fiber diameter. Stages of implementation of the study are (1) the measurement of the diameter of S2K before soaking, (2) immersion S2K in an alkali solution (NaOH) at a concentration of 5%, 10%, 15%, 20%, and 25% for 3 and 5 hours, ( 3) after being soaked, S2K removed and rinsed with distilled water, (4) was dried in a room temperature of 30±2°C for 5 days, (5) the measurement of the diameter of S2K after soaking with digital microscope. Based on the results of tests performed concluded that (1) immersion in an alkali solution resulted in a reduction of the diameter of S2K, (2) on soaking 5 hours at a concentration of 15% NaOH solution obtained reduction diameter S2K largest percentage of 56.08%. Keywords: natural fibers, the concentration of alkali, wettability.

The long-term goal of this research is to makecoconut fiber composite as one of the technical material, forbuilding material such as ceiling board or for automotivematerial such as bumper. While the specific target to be achievedin this research is to determine the influence of the concentrationof alkali solution on soaking coconut fiber to the content of lignin,cellulose, and hemicelluloses of coconut fiber. To achieve theobjectives and targets, the method of implementation of thisresearch is divided into 4 (four) steps, namely (1) preparation, (2)immersion, (3) testing, and (4) analysis. Coconut fiber is treatedby soaking coco fiber for 3 hours in sodium hydroxide (alkali)solution with concentrations of 5%, 10%, 15%, 20%, 25%, 30%,35%, 40%, 45%, 50%, and 55%. Once soaked, the coconut fiberis rinsed with aqua, then dried in an oven at 60°C for 4 hours.After that, a composition test with hydrolysis method todetermine the content of lignin, cellulose, and hemicelluloses.Each variable will be tested 3 (three) times. The data obtainedwill be analyzed statistically by applying descriptive method,where all data obtained will be presented in table, graphic, orimage form. Based on the tables, graphs, and images will beanalyzed and drawn conclusions. The results to be achieved inthis study is to determine the content of lignin, cellulose, andhemicelluloses coconut fiber due to alkali treatment for 3 hourswith a variable concentration of alkali solution. Based on theresults and discussion it can be concluded that soaking coconutfiber in alkaline solution degrades the content of hemicelluloses,cellulose and lignin.

The study is research and development that aims to develop augmented reality-based chemistry learning module which is valid, practical, and effective. Augmented reality-based chemistry learning module refers to the 4-D development model by Thiagarajan et. al., which includes the stages of defining, designing, developing and disseminating. This learning modules had been conducted the validation stage by the assessors or experts and gone through field trial, revised by the developer to produce learning module which is valid, effective, and practical. The results of the study reveal that: (1) the assessments of feasibility or validity of the media expert and a material expert are in the very valid category; (2) in the field trial stage to 33 students of grade XI MIA 1 at SMAN 10 Makassar obtained the mean score of  80.00 learning outcomes from an ideal score of 100 with a grade completeness of 82%; (3) the responses of students and teachers respectively with a percentage of  80.38% and 100%, so the module is stated as practical. Therefore, the conclusion of the study is the augmented reality-based chemistry learning module which had been developed using 4D model is valid, practical, and effective to be applied in learning.

Climate change is a global phenomenon that can be felt locally. The potential impact of climate change is a change in rainfall patterns and an increase in air temperature. One area that is vulnerable to climate change is urban areas, people and development are the driving factors for increasing greenhouse gas emissions. For climate change conditions in Makassar City, it is necessary to analyze the parameters of rainfall and air temperature. The data used are daily rainfall data and air temperature from 1991 - 2020 obtained from UPT BMKG Kelas I Maros. Data analysis was carried out by calculating the trend of rainfall and maximum air temperature, as well as calculating the frequency of rainfall with very heavy intensity (rainfall > 100 mm/day). The results of the analysis show an increase in the value for the rainfall parameter of 8.2 mm/year and the maximum air temperature of 0.0317 °C/year, but there is a decrease in heavy rainfall. Annual rainfall is increasing but the frequency of heavy rains is increasing from the occurrence of rain in Makassar City but will occur more often only with high intensity. Maximum air temperature can cause increased drought in the dry season, and increased rainfall can cause flooding in the rainy season.Keywords: rainfall, air temperature, trend

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