Pengaruh Penambahan Gula Pasir Terhadap Kuat Tekan Dan Sifat Kedap Air Mortar

Penggunanan mortar pada pekerjaan dinding rumah, kamar mandi, ataupun bak air saat ini belum maksimal karena banyak dijumpai retak dan tidak kedap air. Dalam mengatasi masalah ini biasa digunakan bahan kimia tambahan (chemical admixtures), tetapi bahan kimia tersebut harganya mahal dan sulit didapat. Penelitian ini bertujuan untuk mengetahui pengaruh penambahan gula pasir terhadap kuat tekan dan sifat kedap air pada mortar. Benda uji yang dipakai untuk pembuatan mortar berbentuk kubus berukuran 5 x 5 x 5 cm dengan variasi penambahan gula pasir 0%, 0,05%, 0,10%, 0,15%, 0,20%, 0,25%, dan 0,30% dari berat semen. Variasi campuran yang dipakai adalah 1PCC : 4Psr, 1PCC : 6Psr, dan 1PCC : 8Psr. Kuat tekan mortar maksimum adalah kuat tekan mortar dengan penambahan gula pasir 0,10 – 0,15% dan menyebabkan kenaikan kuat tekan 18,4% dari kuat tekan mortar normal. Porositas dan absorpsi mortar yang paling kecil adalah mortar dengan tambahan gula pasir 0,10 – 0,15% . Porositas mortar turun 9,99% dari porositas mortar normal dan absorpsi turun 11,84% dari absorpsi mortar normal

Effects of a science education module on attitudes towards modern biotechnology of secondary school students

This article evaluated the impact of a four-lesson science module on the attitudes of secondary school students. This science module (on cancer and modern biotechnology) utilises several design principles, related to a social constructivist perspective on learning. The expectation was that the module would help students become more articulate in this particular field. In a quasi-experimental design (experimental-, control groups and pre- and post-tests) secondary school students’ attitudes (N=365) towards modern biotechnology were measured by a questionnaire. Data were analyzed using chi-square tests. Significant differences were obtained between the control and experimental conditions. Results showed that the science module had a significant effect on attitudes, although predominantly towards a more supportive and not towards a more critical stance. It is discussed that offering a science module of this kind can indeed encourage students to become more aware of modern biotechnology, although promoting a more critical attitude towards modern biotechnology should receive more attention

Analysis of Runoff Coefficient Value on Retention Ponds in Flores Island

Flores Island is one of four big islands in NTT province with an area ±13,540 km divided into 8 districts. The area is included in areas with unequal distribution of rainfall. Therefore, the amount of water availability during the dry season is relatively low then require to attempts of rainwater harvesting. One of the alternatives is by building a retention pond. The important parameter in the calculation of water availability is the value of runoff coefficient. The purpose of this research is to invent the runoff coefficient value of 30 retention ponds in 8 districts of Flores Island. In this study use rainfall data, climatology and technical of retention basin for the analysis of run off coefficient. The analysis method uses the Penman modification for evapotranspiration calculation and method F.J. Mock for discharge calculation. The result in graphical model uses monthly rainfall data and land slope data. Based on the analytical calculation method, the value of run off coefficient for each district in Flores was ranging 0.00 - 0.72. The minimum value of runoff coefficient happened in November was ranging from 0.00 - 0.39, and the maximum value of runoff coefficient happened in January was ranging from 0.48 - 0.72

Cycloaddition of Strained Cyclic Alkenes and Ortho-Quinones: A Distortion/Interaction Analysis

The chemistry of strained unsaturated cyclic compounds has experienced remarkable growth in recent years via the development of metal−free click reactions. Among these reactions, the cycloaddition of cyclopropenes and their analogues to ortho-quinones has been established as a highly promising click reaction. The present work investigates the mechanism involved in the cycloaddition of strained dienes to ortho-quinones and structural factors that would influence this reaction. For this purpose, we use B97D density functional theory calculations throughout, and for relevant cases, we use spin component−scaled MP2 calculations and single−point domain-based local pair natural orbital coupled cluster (DLPNO-CCSD(T)) calculations. The outcomes are analyzed in detail using the distortion/interaction model, and suggestions for future experimental work are made

On the discontinuous nature of the Mozambique Current

The concept of a spatially continuous western boundary current in the Mozambique Channel has historically been based on erroneous interpretations of ships' drift. Recent observations have demonstrated that the circulation in the Channel is instead dominated by anti-cyclonic eddies drifting poleward. It has therefore been suggested that no coherent Mozambique Current exists at any time. However, satellite and other observations indicate that a continuous current - not necessarily an inherent part of Mozambique Eddies - may at times be found along the full Mozambican shelf break. Using a high-resolution, numerical model we have demonstrated how such a feature may come about. In the model, a continuous current is a highly irregularly occurring event, occurring about once per year, with an average duration of only 9 days and with a vertical extent of about 800 m. Surface speeds may vary from 0.5 m/s to 1.5 m/s and the volume flux involved is about 10 Sv. The continuous current may occasionally be important for the transport of biota along the continental shelf and slope

A New Physical Performance Classification System for Elite Handball Players : Cluster Analysis

The aim of the present study was to identify different cluster groups of handball players according to their physical performance level assessed in a series of physical assessments, which could then be used to design a training program based on individual strengths and weaknesses, and to determine which of these variables best identified elite performance in a group of under-19 [U19] national level handball players. Players of the U19 National Handball team (n=16) performed a set of tests to determine: 10 m (ST(10)) and 20 m (ST(20)) sprint time, ball release velocity (BRv), countermovement jump (CMJ) height and squat jump (SJ) height. All players also performed an incremental-load bench press test to determine the 1 repetition maximum (1RM(est)), the load corresponding to maximum mean power (Load(MP)), the mean propulsive phase power at Load(MP) (P(MPP)MP) and the peak power at Load(MP) (P(PEAK)MP). Cluster analyses of the test results generated four groupings of players. The variables best able to discriminate physical performance were BRv, ST(20), 1RM(est), P(PEAK)MP and P(MPP)MP. These variables could help coaches identify talent or monitor the physical performance of athletes in their team. Each cluster of players has a particular weakness related to physical performance and therefore, the cluster results can be applied to a specific training programmed based on individual needs