TANGGUNG JAWAB GURU DALAM MEMBINA AKHLAK SISWA DI MADRASAH TSANAWIYAH DESA PULAU LAWAS KECAMATAN BANGKINAG KABUPATEN KAMPAR

Abstrak Tidak Tersedi

Reaction kinetics of carbon dioxide with aqueous solutions of l-Arginine, Glycine & Sarcosine using the stopped flow technique

The use of amino acids as potential solvents for carbon dioxide (CO2) capture has been considered by a number of researchers. However, very little is known about the kinetics and mechanism of amino acids-CO2 reactions. In this work, we investigate the reactions of three amino acids (l-Arginine, Glycine and Sarcosine) with CO2 in aqueous media using stopped-flow conductivity technique. The experiments were performed at temperatures between 293 and 313K and amino acids concentrations were in the range of 0.05–0.2 molar. The overall rate constants (kov) was found to increase with increased amino acid concentration and solution temperature. Both zwitterion and termolecular mechanisms were used to model and interpret the data. However, the Zwitterion mechanism was found to be the preferred one. From the stopped-flow results at pH around 6, we found that neutral l-Arginine, Glycine and Sarcosine react with CO2(aq) with k(M−1s−1)=2.81×1010exp(−4482.9T(K)), k(M−1s−1)=3.29×1013exp(−8143.7T(K)) and k(M−1s−1)=3.90×1013exp(−7991.0T(K)) respectively. The corresponding activation energies are 37.28kJmol−1, 67.71kJmol−1 And 66.44kJmol−1 respectively. A comparison between the kinetics of the three amino acids showed that Arginine exhibits highest reaction rate with CO2 followed by Sarcosine and then Glycine. The technique and results obtained from this work can be used as strong tools in the development of efficient new solvents for the removal of CO2 from flue and industrial gases.This paper was made possible by an NPRP Grant # 7-1154-2-433 from the Qatar National Research Fund (a member of Qatar Foundation)

Adsorption of Congo Red Dye Using Activated Carbon-Fe3O4 Composite

Activated Carbon-Fe3O4 composites were synthesized using co-precipitation method and used in batch experiments to adsorb Congo red dyes. The effect of adsorbent dosage, temperature and initial dye concentration was investigated. Increase in the adsorbent dosage resulted in the increase of dye adsorption capacity and the optimum dose was found to be 2 g/L. Increase in temperature had slightly negative impact on the adsorption which indicated the exhothermic nature of the adsorption process. Initial dye concentration also had significant impact on the adsorption process as the adsorption capacity of the AC- Fe3O4 adsorbents decreased with increase in dye concentrations. Finally, the obtained adsorption data were fitted to Langmuir adsorption isotherm and the maximum adsorption capacity of Activated Carbon-Fe3O4 adsorbent was found to be around 129.87 mg/g. Overall, the results suggested that synthesized AC- Fe3O4 composites exhibit significant potential to be used as an adsorbent for the removal of organic pollutants from aqueous solutions

Analysis of Steady-State Characteristics for a Newly Designed High Voltage Gain Switched Inductor Z-Source Inverter

This paper aims to develop a new switched inductor assisted strong boost Z-source inverter (SL-SBZSI) topology with high voltage gain and analyze the steady-state characteristics of the proposed topology. In the proposed topology, two switched inductors are used within the series impedance structure of the Z-source inverter (ZSI) in order to achieve the high voltage gain. The steady-state characteristics of the proposed topology are analyzed to disseminate its several advantages as compared to traditional ZSIs. The key advantages include the higher boost factor with lower shoot-through duty ratio and lower voltage stresses on capacitors as well as on switches of the inverter bridge. Furthermore, the proposed topology has the soft-start ability which significantly reduces the inrush start-up current while comparing with the traditional ZSI. In the proposed topology, a common ground is shared between the output AC voltage and the input DC voltage source which categorizes this topology to the doubly grounded inverter. The characteristics of the proposed SL-SBZSI are analyzed by considering two operating condition where the simple boost pulse width modulation (PWM) scheme is used to extract the shoot-through pulses. The characteristics of the proposed topology are also compared with different existing topologies along with the conventional modified capacitor assisted Z-source inverter (MCA-ZSI), whose boost factor is much closer to the proposed topology. Rigorous mathematical analyses are presented to clearly demonstrate the benefits of the proposed topology while simulation studies are carried out to demonstrate its distinct features as compared to the existing topology. Finally, experimental studies are conducted to further validate the theoretical and simulation results

Effective Heterogeneous Fenton-Like degradation of Malachite Green Dye Using the Core-Shell Fe3O4@SiO2 Nano-Catalyst

In this study, the application of the core-shell Fe3O4@SiO2 nano-catalysts for fenton-like degradation of malachite green dye has been presented. The nano-catalysts were prepared using a combination of solvothermal and sol-gel techniques and characterized using XRD, FTIR, SEM/EDX, TEM and VSM techniques. The effects of various reaction parameters on the degradation of malachite green dye using the prepared nano-catalysts were investigated. The optimal condition for pH, catalyst dosage and H2O2 amount were found to be at 6.7, 15 mg and 50 μL, respectively. Under the optimized conditions, a degradation efficiency of 96.18 % for malachite green dye was achieved using the catalyst within 30 minutes at 303 K with a pseudo first order rate constant of 0.1102 min−1. The plausible mechanism for MG degradation was determined to be the combination of adsorption and simultaneous decomposition via formation of hydroxyl radicals. The performance of the nano-catalyst was compared with other fenton-like catalysts reported in the literature. Finally, the magnetic properties of the Fe3O4@SiO2 catalysts was utilized for its successful recovery and application in multiple degradation cycles.This research was made possible by an NPRP Grant#10-0127-170270 from the Qatar National Research Fund (a member of Qatar Foundation). The statements made herein are solely the responsibility of the authors. The authors would like to acknowledge the help Centre for Advanced Materials (CAM) at Qatar University and Mr. Abdullah Al Ashraf for providing XRD test data. SEM/EDX tests was accomplished in the Central Laboratories unit, Qatar University.Scopu

Adsorption of 4-Nitrophenol onto Iron Oxide Bentonite Nanocomposite: Process Optimization, Kinetics, Isotherms and Mechanism

Despite its importance in chemical industry, 4-Nitrophenol (4-NP) is a persistent organic pollutant that has serious effects on the ecosystem. In the present study, Box–Behnken design in response surface methodology was used to optimize the adsorption process parameters for the maximum 4-NP removal at 30 ℃ using Fe3O4/Bt NC. The regression model results suggested that the optimum adsorbent dosage, initial concentration, pH and contact time were 0.3182 g, 85 mg/L, 11 and 137.2 min, respectively. The regression model showed an optimum removal of 100%, while 99.5% removal was obtained from batch experiments at the optimum conditions suggested by the regression model, which confirm the model validity. The adsorption data best fitted to Freundlich isotherm model and Pseudo second-order kinetic model suggesting the existence of physical and chemical interaction between the fabricated composite and 4-NP. FTIR analysis suggested that the adsorption mechanism included an electrostatic attraction and the formation of new chemical bonds. Obtained results suggest that Fe3O4/Bt NC can be an effective adsorbent for complete 4-NP removal at the indicated optimum conditions.This research was made possible by an NPRP Grant # 10-0127-170270 from the Qatar National Research Fund (a member of Qatar Foundation). The statements made herein are solely the responsibility of the authors. The author Dina Ewis acknowledged the financial support of QNRF through the Graduate Sponsorship Research Award (GSRA) number GSRA#6-2-0516-19029.Scopu

PEMANFAATAN BAHAN ALAMI UNTUK MEMPERPANJANG UMUR SIMPAN IKAN KEMBUNG (Rastrelliger neglectus)

Penelitian ini bertujuan memanfaatkan sosor bebek dan jahe merah sebagai bahan pengawet alami ikan serta mencari rasio terbaik ikan dan es pada penanganan ikan kembung. Penelitian ini memanfaatkan daun sosor bebek (Kalanchoe pinnata Lamk.Pers) dan jahe merah (Zingiber officinalle var. Amarum) sebagai pengawet alami pada ikan kembung (Rastrelliger neglectus) yang didinginkan dengan perbandingan ikan dan es yang berbeda. Perlakuan pada penelitian ini adalah perlakuan sosor bebek 20% dan jahe merah 9%. Ikan kembung disimpan dalam rasio ikan dan es yang berbeda (1:1 (kontrol), 1:1, 3:1, 5:1 (dengan perlakuan bahan alami) selama 12 hari. Parameter yang diamati adalah perubahan organoleptik, TPC, dan TVBN. Perlakuan terbaik dihasilkan dari perlakuan rasio ikan dan es 1:1. Kedua bahan alami dapat digunakan sebagai alternatif untuk memperpanjang shelf-life ikan kembung

Arsenic Exposure of Mothers and Low Birth Weight

Low birth weight (LBW) of the babies was found to be associated with arsenic exposure through consuming arsenic-contaminated water in Bangladesh. But the influences of maternal nutritional status and hemoglobin level remains to be dealt with. This study was conducted to assess the LBW of the babies in reference to arsenic exposure of mothers controlling the influences of the nutritional status (BMI) and hemoglobin level. This was a cross-sectional study carried out amongst the pregnant mothers who came to a district hospital for delivery. The mothers aged ≥18 years and had no complication were included in the study. A total of 101 mothers and their newborn babies were the study sample. Of the total 101 participant mothers, 41.5% were arsenic exposed. Comparatively, on an average, lower birth weight (2492± 477gr) was found among the babies born to arsenic exposed-mother. The exposed mother of LBW babies had significantly a higher urine arsenic concentration (381.38µg/L). The correlation analysis revealed that there was a negative relationship with the urine arsenic concentration (r=-.619; p=.000) and positive relationship with the hemoglobin level (r=.280; p=.092) and BMI (r=.204; p=195) of the exposed mother with the birth weight. After controlling the influence of hemoglobin level and BMI, an almost same association was found between LBW and urine arsenic. Mothers with arsenic exposure were at risk of giving birth to LBW babies, this could increase as evident by higher maternal urine arsenic concentration. And any positive effect of maternal nutritional status and hemoglobin level on birth weight of newborn could be offset by arsenic exposure

Study Of Reaction Kinetics Of Co2 With Aqueous Solutions Glycine , L-Arginine And Their Mdea Blends Using Stopped-Flow Technique

Global warming and its harmful implications is a major concern for the government and scientific community worldwide. CO2 being a greenhouse gas is considered to be a major contributor to the global warming. To reduce the anthropogenic emissions of CO2, capture of CO2 from the industrial processes is a must. The solvent based CO2 capture process is considered to be the most mature and promising technology to capture CO2 from the exhaust streams. Alkanolamines are the most widely used solvents in the CO2 capture processes. However, they are energy intensive and there are still needs for development of novel solvents that can make the CO2 capture technology more energy efficient. Amino acids have recently emerged as potential candidate to be used as an alternative in the CO2 capture technology. Since it is crucial to know the reaction kinetics of a particular amine solvent, before it can be suggested for chemical absorption of CO2, the main focus of this project is to investigate the reaction kinetics of two amino acids, namely; Glycine and L-Arginine with CO2 and their kinetic behavior when they are used in combination of an alkanolamine, such as MDEA, using the stopped flow technique. The experiments were carried out at a temperature range of 293-313 K and different amine/amino acid proportions for a total concentration ranging from 0.5 to 2 mole/L. The obtained kinetic results showed that amino acids and their blends of MDEA have great potential to be used as an alternative solvent for CO2