Development of flipbook e-module problem-based learning (PBL) learning model to increase students’ learning outcomes in oxidation-reduction reaction material

Research and Development has been carried out to produce a valid, practical and effective e-module flipbook model of Problem-Based Learning (PBL) to improve learning outcomes on redox material. This type of research is Research and Development (R&D) adopting the ADDIE development model. The e-module trial was carried out in Class X MIPA at SMA Negeri 12 Banjarmasin for the 2020/2021 Academic Year. Validation and observation sheets, readability questionnaires, response questionnaires, and learning outcomes tests were occupied to collect the data. In analyzing the data, descriptive analysis was used. The results showed that the developed e-module has met the following criteria: (1) Validity; the value of the content feasibility aspect of 91% (very valid), presentation of 96% (very valid), language of 95% (very valid), and media of 94.5% (very valid). (2) Practicality, seen from the readability results of e-module on individual tests of 3.5 (very good) and small groups of 3.4 (very good), student responses to e-modules of 3.3 (very good), and responses to teacher teaching activities using e-module of 3.7 (very good). (3) Effectiveness, views and learning outcomes of knowledge with an N-gain value of 0.80 (high) and the result of learning attitudes of 83.26 (very good).

High electrical conductivity and oxidation reduction reaction activity of tungsten carbide/carbon nanocomposite synthesized from palm oil by solution plasma process

In this study, the enhancement of electrical conductivity and Oxidation Reduction Reaction (ORR) activity of tungsten carbide/carbon (WC/C) nanocomposite was successfully synthesized from palm oil by solution plasma process (SPP). For the synthesis, plasma fields with different frequency were applied the bipolar pulsed power supply connected with two tungsten electrodes. The properties of the synthesized WC/C nanocomposite were varied by using a different frequency. The electrical conductivity increased with the frequencies. The highest electrical conductivity was 4.27×10−2 S cm−1, which is higher than that of Ketjen Black (7.37 × 10−3 S cm−1). The WC/C nanocomposites were observed the surface area 160 m2 g−1, pore volume 0.53 cm3 g−1, average pore diameter 16.29 nm, basal plane crystallite size 18.0 nm, and the average compound granule diameter less than 100 nm. The cyclic voltammetry measurement was showed that the ORR activity of WC/C nanocomposites were obtained the good performance in alkaline solution for fuel cell application.

Pseudomonas aeruginosa transition from environmental generalist to human pathogen

Opportunistic bacteria Pseudomonas aeruginosa is one of the major concerns as an etiological agent of nosocomial infections in humans. Many virulence factors used to colonize the human body are the same as those used by P. aeruginosa to thrive in the environment such as membrane transport, biofilm formation, oxidation/reduction reaction, among others. P. aeruginosa origin is mainly from the environment, the adaptation to mammalian tissues may follow a source-sink evolution model; the environment is the source of many lineages, some of them capable of adaptation to the human body. Some lineages may adapt to humans and go through reductive evolution in which some genes are lost. The understanding of this process may be critical to implement better methods to control outbreaks in hospitals.

Study of Highly Sensitive Formaldehyde Sensors Based on ZnO/CuO Heterostructure via the Sol-Gel Method

Formaldehyde (HCHO) gas sensors with high performance based on the ZnO/CuO heterostructure (ZC) were designed, and the sensing mechanism was explored. FTIR results show that more OH− and N–H groups appeared on the surface of ZC with an increase in Cu content. XPS results show that ZC has more free oxygen radicals (O*) on its surface compared with ZnO, which will react with more absorbed HCHO molecules to form CO2, H2O and, electrons, accelerating the oxidation-reduction reaction to enhance the sensitivity of the ZC sensor. Furthermore, electrons move from ZnO to CuO in the ZC heterostructure due to the higher Fermi level of ZnO, and holes move from CuO to ZnO until the Fermi level reaches an equilibrium, which means the ZC heterostructure facilitates more free electrons existing on the surface of ZC. Sensing tests show that ZC has a low detection limit (0.079 ppm), a fast response/recovery time (1.78/2.90 s), and excellent selectivity and sensitivity for HCHO detection at room temperature. In addition, ambient humidity has little effect on the ZC gas sensor. All results indicate that the performance of the ZnO sensor for HCHO detection can be improved effectively by ZC heterojunction.

ÁLCOOL EM GEL PARA ASSEPSIA DAS MÃOS – FORMULAÇÃO ADEQUADA E EFICIÊNCIA GARANTIDA EM MEIO À PANDEMIA DA COVID-19

ALCOHOL GEL FOR ASEPSY OF THE HANDS – PROPER FORMULATION AND GUARANTEED EFFICIENCY AMID THE PANDEMIC OF COVID-19. The use of hand antiseptics became widespread as a routine in the fight against COVID-19. In the market, the availability and purchase of substandard antiseptics create a permanent concern with safety, even after a pandemic. Therefore, the development of easy-to-deploy analytical methods for the quality control of alcohol-based hand antiseptics is needed. In this work, to determine the ethanol content in alcohol gel the use of refractometry and alcohol oxidation method by dichromate accompanied by UV-Vis spectroscopy were applied. The results indicated that 19 brands (out of the 70 evaluated) (27.1%) had levels of ethyl alcohol below the recommended level (68.25%), therefore, they are ineffective for hand asepsis. For the quality control of hand antiseptics, refractometry and the oxidation-reduction reaction are complementary analytical methodologies. As a quick, inexpensive screening method, refractometry provides a more suitable technique. However, the interference of emollients may affect the accuracy of the ethanol content determination. Therefore, applying the ethanol oxidation method coupled with electronic spectroscopy offers a simple and broadly accessible method to confirm the ethanol content in alcohol-based hand antiseptics. In addition to developing quality control protocols, is also described the 3.5-ton production of alcohol gel at the Federal University of Bahia.

Mixing Performance of Inner Baffle in Shear Thinning Fluid

A mixing performance of an inner baffle was investigated in shear thinning fluid. The inner baffle was placed with a clearance between baffle and vessel wall. A traditional two-bladed paddle impeller was used. Four planar baffles were vertically placed in two ways: 1) standard baffle condition 2) inner baffle condition. The standard baffle condition was that the baffle was placed on the mixing vessel wall. A mixing pattern was visualized by decolorization method based on an oxidation-reduction reaction with sodium thiosulfate and iodine. Flow field for shear thinning fluid in mixing vessel was measured by particle image velocimetry and was shown as stream line. A pair of isolated mixing regions (IMR) like doughnut-ring formed above and below the impeller under standard baffle condition. However, IMR dissipated under inner baffle condition. As a result, a mixing time under the inner baffle condition was drastically decreased. This study suggested that inner baffle promoted mixing in shear thinning fluid.

Henry Taube. 30 November 1915—16 November 2005

Through a lifetime of increasingly broad and significant experiments and discoveries, Henry Taube became the world's premier mechanistic inorganic chemist (one who focuses on reaction pathways and reaction mechanisms produced during inorganic chemical changes). In his first faculty appointment, he examined the oxidation–reduction reaction and identified questions that could only be answered through precise experimentation. He then focused on the chemistry of transition metal complexes, laying out the details of what he called ‘inner sphere electron transfer’. He went on to compile a broad range of findings, leading to the elevation of inorganic chemistry to a major field of study. Taube earned bachelor's and master's degrees at the University of Saskatchewan and a PhD from UC Berkeley. After receiving his doctorate in 1941, he took a position as an instructor at Cornell University, where he remained until 1946. He then joined the faculty of the University of Chicago, where he carried out seminal investigations of the electron transfer reactions between metal ion complexes. In 1962 he moved to Stanford, where he continued studies of electron transfer mechanisms. He also twice served as chair (1972–74; 1978–79) of the Stanford Department of Chemistry and subsequently was appointed the Marguerite Blake Wilbur Professor in 1976. He formally retired from the faculty in 1986, but continued as an active scientist long afterward.