A flipped classroom: learning experiences in programming.

This study explored students' perceptions of a flipped classroom for an introductory programming class. Students were required to watch video lectures and read lecture notes in advance (pre-class self-study) to prepare themselves for the in-class lectures and tutorials. A mix-methods approach was employed: quantitative survey (n=204) and qualitative interview (n=7) were administered simultaneously. The results suggested that students are not fully ready for a flipped classroom. Most of the students still prefer face-to-face in-class lectures and tutorials. The in-class activities have a positive impact on students' test performance, especially the male students. Peer learning however induces a negative impact on students' test performance, especially among the female students. Pre-class self-study has no impact on students' test performance, except for those without prior programming experience. Females outperform males even though they lack prior programming experience. Students, regardless of programming background, respond equally to a flipped classroom approach

One-pot preparation of three-component oil-in-water high internal phase emulsions stabilized by palm-based laureth surfactants and their moisturizing properties

In the present study, olive and olein oils had been used for the preparation of three-component high internal phase emulsions with oil volume fraction of more than 0.77 stabilized by palm-based laureth surfactants for the first time, respectively. These emulsions were easily prepared by one-pot homogenization. The critical micelle concentration and Gibbs energy of the as-synthesized surfactants were determined and discussed. Likewise, the morphology, structural properties, stability and hydration efficacy of the as-prepared emulsions were investigated. Droplet size distribution observed from the optical micrographs was in agreement with the light scattering results which suggested that droplet size increased with increasing ethylene oxide chain length. The rheological measurements of the emulsions at room (25°C) and elevated (40°C) temperatures were interpreted to give clear and direct explanation on the structure and stability of the emulsions. The hydration efficacy of the emulsions was examined in vivo using a corneometer. Both the emulsions containing olive and olein oils, respectively exhibited high stability as indicated by the rheological measurements and the structural properties did not differ from one another. However, olein oil’s hydration efficacy was higher than olive oil’s, suggesting that olein oil could well be a potential moisturizing lipid which might interest the dermatologists

Sucrose ester micellar-mediated synthesis of Ag nanoparticles and the antibacterial properties

Ag nanoparticles with diameter in the range of 10–25 nm had been synthesized using a simple sucrose ester micellar-mediated method. Ag nanoparticles were formed by adding AgNO3 solution into the sucrose ester micellar solution containing sodium hydroxide at atmospheric condition after 24 h of aging time. Trace amount of dimethyl formamide (DMF) in the sucrose ester solution served as a reducing agent while NaOH acted as a catalyst. The produced Ag nanoparticles were highly stable in the sucrose ester micellar system as there was no precipitation after 6 months of storage. The as-synthesized Ag nanoparticles were characterized using transmission electron microscope (TEM), X-ray diffractometer (XRD), dynamic light scattering (DLS) and UV–vis spectroscopy (UV–vis). Formation mechanism of Ag nanoparticles in the micellar-mediated synthesis is postulated. The antibacterial properties of the Ag nanoparticles were tested against Methicillin-resistant Staphylococcus aureus (MRSA) (Gram-positive) and Aeromonas hydrophila (Gram-negative) bacteria. This work provides a simple and “green” method for the synthesis of highly stable Ag nanoparticles in aqueous solution with promising antibacterial property

Facile synthesis of silver nanoparticles under γ-irradiation: effect of chitosan concentration

In the present study, a biopolymer, low molecular weight chitosan had been utilized as a “green” stabilizing agent for the synthesis of silver nanoparticles under γ‐irradiation. The as‐synthesized silver nanoparticles have particle diameters in the range of 5 nm–30 nm depending on the percentage of chitosan used (0.1 wt%, 0.5 wt%, 1.0 wt% & 2.0 wt%). It was found that the yield of the silver nanoparticles was in accordance with the concentration of chitosan presence in the solution due to the reduction by the chitosan radical during irradiation. The highly stable chitosan encapsulated silver nanoparticles were characterized using transmission electron microscopy (TEM), UV‐Visible spectrophotometer (UV‐VIS) and X‐ray diffraction spectroscopy (XRD)

The photodegradation of organic compounds by ZnO nanopowder

The commercialized ZnO nanopowder has been employed in this study to investigate the photocatalytic degradation of two organic compounds, Methylene Blue (MB) and Phenol Red (PR) in an aqueous suspension of ZnO nanoparticles under UV light irradiation. This study has considered ZnO as the photocatalyst because it has been reported as a suitable substitute for TiO2 in certain application. For the characterization of the ZnO photocatalyst, X-ray diffraction (XRD), transmission electron microscopy (TEM), specific surface area analysis (BET), and UV-visible spectroscopy were exploited. X-ray diffractometry result for the ZnO nanoparticles exhibit normal crystalline phase features. All observed peaks can be indexed to the pure hexagonal wurtzite crystal structures, with the space group of P63mc. From the XRD pattern, no diffraction peaks from other impurities have been observed. In addition, TEM measurement shows that most of the nanoparticles are spherical and rod-like in shape and fairly monodispersed. A significant degradation of the organic compounds were observed in the presence of the catalyst without the irradiation of the UV light and the degradation increases significantly when irradiated with the UV light for a certain period of time. Besides, for the same period of irradiation, the photodegradation of the organic compounds was increased as the photocatalyst loading increases. The BET measurement for ZnO was 11.9 m2/g. The effect of some parameters such as initial concentration of organic compounds and photocatalyst loading were also determined

γ-ray assisted synthesis of Ni3Se2 nanoparticles stabilized by natural polymer

Nickel selenide nanoparticles were synthesized using γ-ray irradiation in the presence of natural polymer, chitosan as capping agent. Chitosan is the deacetylated product of chitin, the second most abundant organic resources after cellulose. The nanoparticles were produced using nickel acetate and selenium dioxide and the as-prepared chitosan stabilized nanoparticles were soluble and stable in aqueous solution. The morphology and structure of the nickel selenide nanoparticles were characterized using transmission electron microscope (TEM) and X-ray diffraction (XRD). Optical properties of the nanoparticles were characterized by UV–Visible spectrophotometer and photoluminescent spectroscopy. The XRD result shows that the nickel selenide conformed to Ni3Se2 with crystal structure of rhombohedral. The absorption spectrum of the Ni3Se2 nanoparticles covered from around 300–600 nm which makes it a potential photovoltaic and optoelectronic device material. In this report, γ-ray irradiation provided a “green”, simple and clean route for the synthesis of chitosan stabilized Ni3Se2 nanoparticles. The size and size distribution of the nickel selenide nanoparticles were influenced by the concentration of chitosan and absorbed dose of γ-ray irradiation

γ-ray assisted synthesis of Ni3Se2 nanoparticles stabilized by natural polymer

Nickel selenide nanoparticles were synthesized using γ-ray irradiation in the presence of natural polymer, chitosan as capping agent. Chitosan is the deacetylated product of chitin, the second most abundant organic resources after cellulose. The nanoparticles were produced using nickel acetate and selenium dioxide and the as-prepared chitosan stabilized nanoparticles were soluble and stable in aqueous solution. The morphology and structure of the nickel selenide nanoparticles were characterized using transmission electron microscope (TEM) and X-ray diffraction (XRD). Optical properties of the nanoparticles were characterized by UV–Visible spectrophotometer and photoluminescent spectroscopy. The XRD result shows that the nickel selenide conformed to Ni3Se2 with crystal structure of rhombohedral. The absorption spectrum of the Ni3Se2 nanoparticles covered from around 300–600 nm which makes it a potential photovoltaic and optoelectronic device material. In this report, γ-ray irradiation provided a “green”, simple and clean route for the synthesis of chitosan stabilized Ni3Se2 nanoparticles. The size and size distribution of the nickel selenide nanoparticles were influenced by the concentration of chitosan and absorbed dose of γ-ray irradiation

γ-ray assisted synthesis of silver nanoparticles in chitosan solution and the antibacterial properties

In the present study, chitosan had been utilized as a “green” stabilizing agent for the synthesis of spherical silver nanoparticles in the range of 5–30 nm depending on the percentage of chitosan used (0.1, 0.5, 1.0 and 2.0 wt%) under γ-irradiation. X-ray diffractometer identified the nanoparticles as pure silver having face-centered cubic phase. Ultraviolet–visible spectra exhibited the influence of γ-irradiation total absorbed dose and chitosan concentration on the yield of silver nanoparticles. The antibacterial properties of the silver nanoparticles were tested against Methicillin-resistant Staphylococcus aureus (MRSA) (gram-positive) and Aeromonas hydrophila (gram-negative) bacteria. This work provides a simple and “green” method for the synthesis of highly stable silver nanoparticles in aqueous solution with good antibacterial property

Three-dimensional flower-like brushite crystals prepared from high internal phase emulsion for drug delivery application

In the present study, three-dimensional brushite crystals were prepared through palm olein-in-water high internal phase emulsion processing route for the first time. X-ray diffraction patterns revealed that the powders possessed brushite crystalline phase with trace amount of hydroxyapatite. Unique morphologies of the brushite crystals were obtained as a result of tailoring the precursor concentration, surfactant concentration and oil volume fraction. These factors governed the rate of nucleation and crystal growth, resulting in flower-like morphologies. The petal-like flakes grew radially from the centre which gave rise to porosity of less than 2 μm. A plausible mechanism of crystal growth is discussed and postulated schematically. Sodium ampicillin, a broad spectrum antibiotic, was loaded into the pores of the crystals, which was subsequently released in vitro. The controlled release ability for up to 14 days indicated the potential of using these brushite crystals as drug delivery agents for localized treatments

Preparation and characterization of brushite crystals using high internal phase emulsion

Various morphologies of brushite crystals were successfully synthesized using oil-in-water high internal phase emulsion stabilized by surfactants with various polyoxyethylene chain lengths for the first time. Rheological measurements had proven that such emulsion was a highly stable reaction media for the synthesis of particulate and porous brushite crystals. Rheological properties of the emulsion with and without the presence of crystal growth were compared and discussed. Morphologies of brushite crystals comprised of leafletlike particles to continuous dendritic network structure which gave rise to porosity in submicron size with increasing polyoxyethylene chain length. The mechanism leading to the various types of morphologies produced is discussed schematically based on small angle X-ray scattering results