Pengembangan Novel Grafik Elektronik pada Materi Reaksi Radikal Bebas sebagai Media Suplemen Pembelajaran

This research was aimed to produce a valid electronic graphic novel on free radical reaction subject and to find out the student’s response to the developed product. This research employed Research & Development (R&D) method by using Thiagarajan’s 4D model with modification, in which applied only three of four steps in 4D model. The developed product was validated by experts. The responses toward developed product were collected from the students of Chemistry Education FKIP Untan who have taken organic chemistry course. Data collection tools used were validation sheets and student’s response questionnaires on the developed product. The validation’s result from the experts showed that the developed product was very proper in terms of content, presentation, linguistic, and graphic aspects with consecutive total scores of 94.0%, 95.0%, 89.0%, and 100,00% respectively. The results of the student’s responses in small group trials and in large group trials were of 82.5% with high category and of 83.2% with very high category, respectively. Thus, this electronic graphic novel on radical reaction has very good potential as a learning media to attract students to learn free radical reaction and its application in daily life.

Investigation of OH radical kinetics with glycine, alanine, serine and threonine in the aqueous phase

<p>Amino acids are key substances in biological activities and can be emitted into the atmosphere as constituents of primary aerosols. Understanding the radical kinetics of amino acids is necessary to evaluate their atmospheric effects. In the present study, the hydroxyl radical (OH) reaction kinetics of glycine, alanine, serine and threonine were investigated in the aqueous phase. The temperature and pH dependent rate constants were measured by a laser flash photolysis-long path absorption setup using the competition kinetics method. Based on the measurements and speciation calculations, the OH radical reaction rate constants of the fully protonated (H<sub>2</sub>A<sup>+</sup>) and neutral (HA<sup>±</sup>) form were determined. The following T-dependent Arrhenius expressions were derived for the OH radical reactions with glycine, <em>k</em>(<em>T</em>, H<sub>2</sub>A<sup>+</sup>) = (9.1 ± 0.3) × 10<sup>9</sup> × exp[(-2360 ± 230 K)/<em>T</em>], <em>k</em>(<em>T</em>, HA<sup>±</sup>) = (1.3 ± 0.1) × 10<sup>10</sup> × exp[(-2040 ± 240 K)/<em>T</em>]; alanine, <em>k</em>(<em>T</em>, H<sub>2</sub>A<sup>+</sup>) = (1.0 ± 0.1) × 10<sup>9</sup> × exp[(-1030 ± 340 K)/<em>T</em>], <em>k</em>(<em>T</em>, HA<sup>±</sup>) = (6.8 ± 0.4) × 10<sup>10</sup> × exp[(-2020 ± 370 K)/<em>T</em>]; serine, <em>k</em>(<em>T</em>, H<sub>2</sub>A<sup>+</sup>) = (1.1 ± 0.1) × 10<sup>9</sup> × exp[(-470 ± 150 K)/<em>T</em>], <em>k</em>(<em>T</em>, HA<sup>±</sup>) = (3.9 ± 0.1) × 10<sup>9</sup> × exp[(-720 ± 130 K)/<em>T</em>]; and threonine, <em>k</em>(<em>T</em>, H<sub>2</sub>A<sup>+</sup>) = (5.0 ± 0.1) × 10<sup>10</sup> × exp[(-1500 ± 100 K)/<em>T</em>], <em>k</em>(<em>T</em>, HA<sup>±</sup>) = (3.3 ± 0.1) × 10<sup>10</sup> × exp[(-1320 ± 90 K)/<em>T</em>] (in units of L mol<sup>-1</sup> s<sup>-1</sup>).</p> <p>The density functional theory calculation was performed using GAUSSIAN to simulate the energy barriers (<em>E<sub>Barrier</sub></em>) of OH radical induced H-atom abstraction. According to the simulated results, amino and carboxyl group increase the <em>E<sub>Barrier</sub></em> at the adjacent C‑atom and thus reduce the OH radical reactivity. Hydroxide and methyl group decrease the <em>E<sub>Barrier</sub></em> at the adjacent C-atom, leading to an increase in the OH radical rate constant.</p>

Removal of Trithiocarbonyl End Group of RAFT-Polymerized Poly(stearyl acrylate) and Effect of the End Group on Thermal and Structural Properties

The effect of a long alkyl end group on the thermal and structural properties of RAFT (reversible addition-fragmentation chain transfer)-polymerized poly(stearyl acrylate) (PSA) was investigated. RAFT-polymerized PSA was prepared using 2-cyano-2-[(dodecylsulfanylthiocarbonyl) sulfanyl] propane (CDTP) with long alkyl group as a chain transfer agent and azobisisobutyronitrile (AIBN) as an initiator. The RAFT polymerization resulted in the polymerized structure having trithiocarbonyl (TTC) at one end and isobutyronitrile at the other end. RAFT-polymerized PSA was prepared with two different molecular weights. The TTC end group was replaced by isobutyronitrile using radical reaction with AIBN through optimization of the conditions, which resulted in isobutyronitrile at both ends. The effect of the end group on the thermal and structural properties was investigated using differential scanning calorimetry and X-ray diffraction, and the results indicated that the long alkyl group from TTC lowers the melting point and semi-crystalline structure in the case of low molecular weight PSA.

The Effects of Combined Fruit-Infused Water (Apple, Pineapple, Strawberry, Cucumber) on Blood Pressure and Fasting Blood Glucose in Patients with Metabolic Syndrome

ABSTRACTBackground: Fruit-infused water (FIW) contains antioxidants and potassium as a antihyperglycemic and antihypertension via inhibition or break the chain of radical reaction but has not been proven in patients with MS.Purpose: To evaluate the effects of FIW on blood pressure and fasting blood glucose (FBG) in patients with MS.Method: This is a Randomized-Control Trial with pre-posttest control group design. 24 patients of Cakranegara Health Center who fulfilled the criteria were randomly divided into control (given counseling only) and treatment (counseling + FIW consists of apple, cucumber, pineapple and strawberry in 250 ml water for 14 days) groups. Blood pressure and FBG were measured before and after intervention. Chi Square was used for descriptive analyze, whereas T-test, Mann Whitney and Wilcoxon was used for differences in means.Result: In the treatment group (n=11), systolic and diastolic mean levels were decreased by 5,4 mmHg (p=0,140) and 0,9 mmHg (p=0,792) respectively. However, FBG levels were increased by 9,2 mg/dL (p=0.929). There were no differences on systolic (p=0,448), diastolic (p=0,835) and FBG (p=0,599) between two groups.Conclusion: FIW consumption are unable to improve blood pressure and FBG levels on metabolic syndrome. Keywords: Fruit-Infused Water, Blood Pressure, Fasting Blood Sugar Level, Metabolic Syndrome

Chemiluminescence Detection in the Study of Free-Radical Reactions. Part 1

The present review, consisting of two parts, considers the application of the chemiluminescence detection method in evaluating free radical reactions in biological model systems. The first part presents a classification of experimental biological model systems. Evidence favoring the use of chemiluminescence detection in the study of free radical reactions, along with similar methods of registering electromagnetic radiation as electron paramagnetic resonance, spectrophotometry, detection of infrared radiation (IR spectrometry), and chemical methods for assessing the end products of free radical reactions, is shown. Chemiluminescence accompanying free radical reactions involving lipids has been the extensively studied reaction. These reactions are one of the key causes of cell death by either apoptosis (activation of the cytochrome c complex with cardiolipin) or ferroptosis (induced by free ferrous ions). The concept of chemiluminescence quantum yield is also discussed in this article. The second part, which is to be published in the next issue, analyzes the application of chemiluminescence detection using luminescent additives that are called activators, a.k.a. chemiluminescence enhancers, and enhance the emission through the tripletsinglet transfer of electron excitation energy from radical reaction products, followed by light emission with a high quantum yield.

Recent advances in the synthesis of 5'-deoxynucleoside phosphonate analogs

: The present review focuses on the synthesis of cyclic 5-deoxynucleoside phosphonate analogs. The formation of various phosphonate alkyl moieties is accomplished through (i) Wittig (or HWE) type condensation to the nucleoside aldehyde moiety; (ii) nucleophilic displacement reaction using phosphonate anion or Lewis acid; (iii) Arbuzov reaction; (iv) olefin cross-metathesis between vinyl phosphonates and vinylated nucleosides; and (v) radical reaction and Pd catalyzed alkyne. For the coupling of nucleobases with cyclic moieties, the Mitsunobu reaction, and Sonogashira-type cross-coupling are usually applied. For the coupling of furanose moieties with nucleobases, Vorbrüggen-type condensation is generally applied. Addition reactions mediated by selenium ions are mainly applied for the coupling of carbocyclic moieties. Their biological activity results are summarized.