Renewable Silica-Carbon Nanocomposite and Its Use for Reinforcing Synthetic Wood Made of Rice Straw Powders

The current study was aimed to prepare and to characterize a renewable silica-carbon nanocomposite from rice straw ashes. It was purposed also to study the use of the produced nanocomposite as reinforcing material in producing a synthetic wood made of three axial blend of treated rice straw powder, phenolfrmaldehyde resin, and the nanocomposite. A simple preparation route of nanocomposite silica-carbon from rice straw was formulated containing three steps, namely pretreating of rice straw, preparing of ultra fine amorphous black silica, and composing silica-carbon nanocomposite. The nanocomposite product was characterized using XRD, XRF, FTIR and SEM methods. The characterization results comfirmed that the silica-carbon nanocomposite was succesfully prepared. The utilizing of the nanocomposite as reinforce material in producing synthetic woods was conducted through hot-pressing some three axial blend compositions of the pretreated rice straw powder, phenolformaldehyde resin, and the nanocomposite. The synthetic wood products were characterized their physical and mechanical properties. As a result, the addition of the nanocomposite could improve the properties of the synthetic wood products

Synthese und Charakterisierung von binären und ternären Verbindungen im System Metall-Silicium-Kohlenstoff

Im Mittelpunkt der vorliegenden Arbeit stehen Darstellung und Charakterisierung von neuartigen keramischen Verbindungen im System Metall-Silicium-Kohlenstoff (Metall = Co,Cr, Al, Ca, Mg und Ba). Die Darstellung erfolgte bei hohen Temperaturen aus den Edukten Metall, Silicium und Kohlenstoff (bzw. Siliciumcarbid) unter reduzierenden Bedingungen (Hochtemperatursynthese). Die Reaktionsprodukte wurden mittels Röntgenbeugung und Elektronenmikroskopie charakterisiert. Bei der Charakterisierung lag der Schwerpunkt der Untersuchungen auf der Pulverbeugung mit anschließender Rietveld-Verfeinerung der aus kommerziellen Laborgeräten (Cu Ka1-Strahlung) und Synchrotron-Messungen am Hasylab(DESY, Hamburg) erhaltenen Beugungsdiagramme. Ausgehend vom Siliciumcarbid wurde ein neues Verfahren zur Darstellung von b-SiCPulver aus Silicium-reichen nachwachsenden Rohstoffen (z. B. Reishülsen und Bambusstamm)untersucht. So konnten b-SiC-Pulver aus carbonisierten Reishülsen und Bambusstamm durch vierstündige Reaktion im Vakuum bei 1500°C dargestellt werden. Durch Ca- sowie Mg-Dotierungen von b-SiC wurde nach Sintern (1950°C; 2 h; Vakuum) die Bildung von a-SiC beobachtet. Untersuchungen im System Co-Si-C (Temperaturbereich: 1200-1800°C) führen zu keiner ternären Verbindung. Hingegen konnte bei einer Reaktionstemperatur von 1400°C eine neue Modifikation von CoSi neben b-SiC und Kohlenstoff dargestellt werden. Die Strukturaufklärung durch Cu Ka1- und Synchrotronröntgenstrahlung ergab eine kubische Modifikation im CsCl-Typ mit der Raumgruppe Pm-3m und dem Gitterparameter a = 281,62(2) pm. Eine Härteprüfung nach Vickers zeigt, dass die CoSi(CsCl-Typ)-Modifikation im Vergleich zur umgehenden SiC/C-Matrix eine deutlich geringere Härte aufweist, die der Härte von intermetallischen Verbindungen vergleichbar ist. Bandstrukturrechnungen liefern einen Wert von 0,8 eV für die Bandlücke, der typisch für einen Halbleiter ist und zwischen Silicium (1,1 eV) und Germanium (0,72 eV) liegt. Untersuchungen im System Cr-Si-C (Temperaturen:1000-1800°C) zeigen, dass vielphasige Reaktionsprodukte entstehen, die eine ternäre Verbindung CrxSiyCz neben Cr3C2,Cr3Si, und SiC erhalten. Bei einer Umsetzung der Edukte im Verhältnis Cr:Si:b-SiC = 5:2:1(1200°C, 40 h; Vakuum) entsteht ein zweiphasiges Sinterprodukt mit ~92 Masse-% der ternären Verbindung Cr5Si2,3C0,3 und ~8 Masse-% b-SiC. Die ternäre Verbindung kristallisiert hexagonal(Raumgruppe: P63/mcm (Nr. 193); Gitterparameter a = 698,45(2) pm, c = 474,07(1) pm und ist isostrukturell zu der Verbindung Mo4,8Si3C0,6. Keramisches Komposit-Material auf Basis von Al-Si-C ist aufgrund einer Vielzahl von ausgezeichneten Materialeigenschaften heute bereits von großem technischem Interesse. Bislang verhindert allerdings die häufig auftretende Bildung von hydrolyseempfindlichem Aluminiumcarbid Al4C3 eine breitere technische Anwendung. Aus diesem Grund lag es nahe die Darstellung der Al4SiC4/SiC-Matrix zu optimieren. Es konnte gezeigt werden, dass bei der Reaktion von elementarem Aluminium, Siliciumcarbid und Kohlenstoff bei einer Temperatur von 1450°C über acht Stunden im Vakuum die Bildung von Al4C3 unterdrückt wird und einzig die gewünschte Al4SiC4/SiC-Matrix entsteht.Main focusses of the present work are the preparation and characterization of some new ceramic compounds in the metal-silicon-carbon system (metals: Co, Cr, Al, Ca, Mg and Ba). The preparation was conducted using metals, silicon and carbon (as well as silicon carbide) at high temperatures under reducing conditions (high temperature synthesis). The reaction products were characterized by X-ray diffraction and electron microscopy. The characterization was emphasized by powder diffraction followed by a Rietveld refinement. The diffraction data were received from commercial laboratory instruments (Cu Ka1 radiation) and synchrotron measurements at the Hasylab (DESY, Hamburg). Outgoing from the silicon carbide a new procedure for directly synthesizing of b-SiC powder from high silicon content of regenerating raw materials (e.g. rice husks and bamboo trunk) was investigated. b-SiC powders from carbonized rice husks and bamboo trunk could be synthesized by a four hour reaction at 1500°C under vacuum. Through doping b-SiC with magnesium as well as calcium the formation of a-SiC was observed after sintering (1950°C; 2 h; vacuum). Investigations in the system Co-Si-C (temperature range: 1200-1800°C) lead to no ternary compound. However a new modification of CoSi could be produced beside b-SiC and carbon at the reaction temperature of 1400°C. The structure clarification by using X-ray diffraction with Cu Ka1 as well as synchrotron beam resulted that the compound crystallizes in a cubic system (CsCl type) with the space group Pm-3m and the lattice parameter a = 281.62(2)pm. A hardness test by the Vickers method showed that the CoSi(CsCl type) modification in the comparison to the SiC/C matrix exhibits a clearly less hardness, which is comparable to the hardness of intermetallic compounds. Band structure calculations supplied a value of band gap ~ 0.8 eV, which is typical for a semiconductor and it lies between the band gap of silicon (1.1 eV) and germanium (0.72 eV) . Investigations in the system Cr-Si-C (temperature range:1000-1800°C) showed that multiphase reaction products which consist of a ternary compound CrxSiyCz beside Cr3C2, Cr3Si,and SiC were developed. By reacting the starting materials with a molar ratio Cr:Si:b SiC = 5:2:1 (1200°C, 40 h; vacuum), a two phase sinter product consisting of the ternary compound Cr5Si2.3C0.3 (~92 mass-% ) and b-SiC (~8 mass-%) was obtained. The ternary compound crystallizes hexagonally (space group: P63/mcm (no. 193); lattice parameter a = 698.45(2) pm, c = 474.07(1) pm and it is isostructural to the compound Mo4.8Si3C0.6. Currently, Al-Si-C based ceramic composite materials are technically of big interests due to their multiple excellent material properties. So far, however, a broader technical use was limited by the frequently presence of the hydrolysis sensitive aluminum carbide Al4C3. For that reason it needs to optimize the preparation method in order to produced an Al4SiC4/SiC matrix without Al4C3. It could be shown that the formation of Al4C3 was supperessed through the eight hour reaction of elementary aluminum, silicon carbide and carbon at a temperature of 1450°C under vacuum and only the desired Al4SiC4/SiC matrix was developed

Pengaruh Model Pembelajaran Kooperatif Tipe Stad Berbantuan Lks Terhadap Pemahaman Konsep Kimia Ditinjau Dari Motivasi Berprestasi

The study was aimed to analyze the effect of cooperative learning model of type student team achievement divisions assisted by student worksheet to comprehension chemistry concept understanding in term of achievement motivation. The research is the design of non-equivalent post test only control group design by ANOVA test with two tiles. Population are students of class X in SMA Negeri 2 Negara totaled 273 people divided into 7 classes and a sample of 234 people were divided into 6 classes. The results are: 1) there are differences in the value of understanding chemistry concepts that students taught with cooperative learning model student teams achievement divisions aided student worksheets, cooperative student teams achievement divisions without student worksheets, and direct instructional model in the group of students who have high achievement motivation with a group of students who have low achievement motivation, (2) there were interaction between learning model and learning achievement motivation on the chemistry concept understandin

Mengembalikan Kejayaan Industri Kerajinan Cadas Silakarang di Kabupaten Gianyar melalui Penerapan Teknologi Cadas Termokromik Buatan

Covid-19 pandemi affects most of craft industries, including the formerly fabulous Silakarang stone’s arts and crafts located in the Gianyar Regency, Bali Province. Environmental issues regarding to river basin ecological protection along Ubud and Sukawati Districts, the mining of basaltic stones from the river banks was restricted strictly by the government. Thus, the natural stones resources for the Silakarang crafts became more difficult to afford. Hence, todays the Silakarang stone craftsmen are more and more dependent on the so-called white stone of Yogya from Java Island. Artificial stone, composing of volcanic ashes, rice husk ash silica-carbon nanocomposite, Portland cement could be the solution the problem. The addition of thermochromic natural inorganic pigment to the mixture could improve their color and performance of the artificial stones. The implementation of the thermochromic artificial stones technology to solve the stone crafts problem was conducted through community service using the participatory action and learning system approuch. As results, the artificial thermochromic stone crafts and arts products could be well accepted by costumers and it impacted to better selling of the stone crafts. The craftsmen gained better income and the Silakarang stone arts and crafts enterprises could better survive among the pandemic time

Pengaruh Model Pembelajaran Berbasis Proyek Terhadap Kecerdasan Emosional Siswa

This study aimed to investigate the effect of project-based learning model for emotional intelligence of students in science learning. This research was a quasi-experimental design with pretest-posttest non-equivalent control group design. The research population was a student of class VII in SMP Negeri 6 Negara with a sample of 124 students were divided into experimental and control groups. The instrument used to determine the emotional intelligence is a multiple choice test free content. The data obtained in the form g-score normalized. Analyses were performed using ANOVA one-way. Based on the analysis, an increase in the average value of each aspect of emotional intelligence in the experimental class and the control class. Increase in the average value of the experimental class is quite significant compared to the control class. Based on the analysis of the data, obtained F calculated is 1491.278. Figures F calculated is greater than F table (3.89) at the 0.05 significance level so that it can be concluded that, there is a difference between the emotional intelligence of students learning with project-based learning model and conventional learning models

Analisis Standar Laboratorium Kimia Dan Efektivitasnya Terhadap Capaian Kompetensi Adaptif Di Smk Negeri 2 Negara

This research was aimed to analyze facilitycarrying capacity, intensity of using laboratory, use factor equipment and chemical, laboratory management, and effectiveness chemistry laboratory standard to adaptive competence achievement.in SMK Negeri 2 Negara. This research was ex-post facto. Laboratory carrying capacitythat appropriate laboratory standard include rooms and common facility is 53% (less category),equipmentsis 45% (less category), andchemical is48% (less category).Intencity using laboratoryin 2012/2013 study yearinclass X is 33.3% (less category), class XIis 100% (very high category), and class XIIis59.3% (enough category). Equipment use factor is 58% (enough category) andchemical is 75.3% (high category). Laboratory management less optimal.The result ofsubsections of laboratory standard in SMK Negeri 2 Negara is effective to adaptive competence achievement. If equipment and chemical needed are available and or substituted, the average of student test comprehension score is 80.3 (higher than KKM)

Faktor risiko dan asupan isoflavon pada pasien kanker payudara

Background: Breast cancer is noncommunicable chronic disease the prevalence of which is increasing all over the world, including in Indonesia and particularly East Java. Causes of breast cancer are unknown. Some studies show risk factors for breast cancer are hormonal, genetic, reproductive and endocrinologic factors. There is the isoflavon compound in soybeans that is known as anti-cancer with anti-estrogen activities.Objective: The study was aimed at identifying risk factor and the difference of isoflavone intake between breast cancer patients and healthy people in hospitals.Method: The study was analytic observational using matched case-control study design at comparison 1:2 with matching on a status of menopause. Cases were positive receptor estrogen breast cancer patients newly diagnosed during the first visit at hospital outpatient Oncologic Surgery Polyclinic. Controls were staff considered healthy based on the result of health examination at Dr. Ramelan Naval Hospital of Surabaya. Cases comprised 49 people and control 98 people taken through consecutive method. Data consisted of an identity of samples, weight, height, isoflavone intake, family history, use of hormone replacement therapy and parity. Intake of isoflavones was obtained from semiquantitative food frequency questionnaire (SQ-FFQ) and statistical test used Chi-Square and Odd Ratio (OR).Results: There was the difference in isoflavone intake and family history between cases and controls (p<0.05) and there was an association between isoflavone intake (OR=2.58; p=0.007) and family history (OR=18; p=0.002) and the incidence of breast cancer. There was no association between the status of obesity, parity, and use of hormone replacement therapy.Conclusion: There are differences in isoflavone intake of breast cancer patients compared with healthy people and there was no difference in the status of obese breast cancer patients compared to healthy individuals and isoflavone intake less 2.85 times the risk of breast cancer compared with adequate intake of isoflavones

Komparasi Literasi Sains Antara Siswa Yang Dibelajarkan Dengan Model Pembelajaran Kooperatif Tipe Gi (Group Investigation) Dan Model Pembelajaran Inkuiri Terbimbing (Guided Inquiry) Dintinjau Dari Motivasi Berprestasi Siswa SMP

Penelitian ini bertujuan untuk mengetahui keunggulan komparasi literasi sains antara siswa yang dibelajarkan dengan model pembelajaran kooperatif tipe GI (Group Investigation) dan model pembelajaran Inkuiri Terbimbing (Guided Inquiry) ditinjau dari motivasi berprestasi siswa SMP. Penelitian eksperimen ini dilaksanakan di SMP Negeri 2 Banjarangkan semester 2 tahun pelajaran 2014/2015, dengan rancangan The Posttest-Only Control Group Design dan faktorial 2x2 sebagai desain penelitiannya. Kelas yang digunakan sebagai sampel ditentukan dengan tehnik Cluster Sampling. Variabel bebas dalam penelitian ini adalah model pembelajaran kooperatif tipe GI (group investigation) yang dikenakan pada kelompok eksperimen dan model pembelajaran Inkuiri Terbimbing yang dikenakan pada kelompok kontrol. Motivasi berprestasi berperan sebagai moderator, yang dipilah menjadi dua tingkatan, yaitu motivasi berprestasi tinggi dan rendah. Sebagai variabel terikat adalah literasi sains siswa. Data motivasi berprestasi siswa dikumpulkan dengan kuisioner motivasi berprestasi dan data literasi sains siswa dikumpulkan dengan menggunakan tes literasi sains. Data yang dikumpulkan dianalisis dengan analisis Varians (ANAVA) dua jalur. Hasil penelitian menunjukkan sebagai berikut: (1) terdapat perbedaan signifikan literasi sains antara kelompok siswa yang mengikuti model pembelajaran kooperatif tipe GI dan kelompok siswa yang mengikuti model pembelajaran inkuiri terbimbing, (2) terdapat interaksi antara model pembelajaran dan motivasi berprestasi terhadap literasi sains, (3) tidak terdapat perbedaan yang signifikan literasi sains antara kelompok siswa yang mengikuti model pembelajaran kooperatif tipe GI dan kelompok siswa yang mengikuti model pembelajaran inkuiri terbimbing pada siswa yang memilliki motivasi berprestasi tinggi, (4) terdapat perbedaan yang signifikan literasi sains antara kelompok siswa yang mengikuti model pembelajaran kooperatif tipe GI dan kelompok siswa yang mengikuti model pembelajaran inkuiri terbimbing pada siswa yang memilliki motivasi berprestasi rendah. Berdasarkan temuan hasil penelitian, disimpulkan bahwa model pembelajaran dan motivasi berprestasi mempunyai pengaruh yang cukup besar terhadap literasi sains. Selanjutnya disarankan kepada guru IPA sebelum merancang model pembelajaran agar motivasi berprestasi tinggi menggunakan model pembelajaran tipe GI atau Inkuiri Terbimbing sedangkan siswa yang mempunyai motivasi berprestasi rendah menggunakan model pembelajaran kooperatif tipe GIKata Kunci : Model Pembelajaran, Motivasi Berprestasi, dan Literasi Sains This study aims to determine the comparative advantages of scientific literacy among students that learned by cooperative learning model GI (Group Investigation) and Guided Inquiry learning model (Guided Inquiry) in terms of achievement motivation junior high school students. This experimental study was conducted in SMP Negeri 2 Banjarangkan second semester of the academic year 2014/2015, using The Posttest-Only Control Group Design and as a 2x2 factorial design study. Classes are used as the sample is determined by cluster sampling technique. The independent variable in this study is a cooperative learning model GI (Group Investigation) imposed in the experimental group and Guided Inquiry learning model imposed in the control group. Achievement motivation role as moderator, which divided into two levels: high and low achievement motivation. As the dependent variable is the science literacy of students. Data collected by student achievement motivation achievement motivation questionnaire and data collected by the scientific literacy of students using science literacy test. The data collected were analyzed by analysis of variance (ANOVA) and two lanes. The results showed as follows: (1) there is a significant difference in scientific literacy among groups of students who take the GI cooperative learning model and a group of students who take the guided inquiry learning model, (2) there is an interaction between the model of learning and achievement motivation toward science literacy, ( 3) there is no significant difference in scientific literacy among the group of students who follow the GI cooperative learning model and the group of students who take the guided inquiry learning model student who has a high achievement motivation, (4) there is a significant difference in scientific literacy among the group of students who take GI cooperative learning model and a group of students who take the guided inquiry learning model student who has a low achievement motivation. Based on the research findings, it was concluded that the model of learning and achievement motivation have considerable influence on science literacy. Furthermore, it is suggested to science teacher before designing a learning model that uses high achievement motivation learning model GI type or Guided Inquiry whereas students with low achievement motivation using cooperative learning model type G