Concept mapping a potential pedagogical strategy to foster meaningful learning in physiology students.

BACKGROUND: Understanding of human physiology is critical for clinical practice and disease management. Escalating the teaching-learning method to improve conceptual knowledge may help the students to apply their knowledge in clinical scenarios. The present study was conducted to teach the use of concept mapping as a learning strategy to foster meaningful learning in physiology, compare its impact as a learning tool with traditional methods on meaningful learning, assess the cognitive gain, and find student's perception regarding concept mapping. MATERIALS AND METHODS: The interventional study was conducted on first-year MBBS students. Depending upon marks obtained in previous internal assessments, the students were classified into "rapid learners" (RL) and "potential learners" (PL). By simple random sampling technique, both groups were divided into interventional (concept mapping) and control groups (question-answer discussion). After a pretest, all students had a lecture on glomerular filtration. The assignment was given to the interventional group to prepare a concept map on glomerular filtration, and question-answer were discussed for control groups. A surprise posttest was conducted after 2-3 days. RESULT: In our study, all four groups showed significant differences in the pretest and posttest scores using a paired t-test (P < 0.05). The mean score of gain in learning, raw gain (G0), absolute learning gain, relative learning gain, and average normalized gain compared between the interventional group and controls group showed statistically significant performance improvement in both RL and PL groups. CONCLUSION: The concept mapping strategy was more efficacious than the question-answer discussion. Concept mapping is an impactful learning tool to improve cognitive gain and potential pedagogical strategy to foster meaningful learning in physiology students.

Fabrication of Mesoporous C60/Carbon Hybrids with 3D Porous Structure for Energy Storage Applications.

We report on the synthesis of 3D mesoporous fullerene/carbon hybrid materials with ordered porous structure and high surface area by mixing the solution of fullerene and sucrose molecules in the nanochannels of 3D mesoporous silica, KIT-6 via nanotemplating approach. The addition of sucrose molecules in the synthesis offers a thin layer of carbon between the fullerene molecules which enhances not only the specific surface area and the specific pore volume but also the conductivity of the hybrid materials. The prepared hybrids exhibit 3D mesoporous structure and show a much higher specific surface area than that of the pure mesoporous fullerene. The hybrids materials are used as the electrodes for supercapacitor and Li-ion battery applications. The optimised hybrid sample shows an excellent rate capability and a high specific capacitance of 254 F/g at the current density of 0.5 A/g, which is much higher than that of the pure mesoporous fullerene, mesoporous carbon, activated carbon and multiwalled carbon nanotubes. When used as the electrode for Li-ion battery, the sample delivers the largest specific capacity of 1067 mAh/g upon 50 cycles at the current density of 0.1 A/g with stability. These results reveal that the addition of carbon in the mesoporous fullerene with 3D structure makes a significant impact on the electrochemical properties of the hybrid samples, demonstrating their potential for applications in Li-ion battery and supercapacitor devices.

Cyclohexylation of Resorcinol with Cyclohexanol Catalyzed by Tungstophosphoric Acid Supported Zirconia Catalysts.

We demonstrate a highly active and reusable heterogeneous catalyst system, tungstophosphoric acid (TPA) supported on zirconia (ZrO2), for the cyclohexylation of resorcinol by cyclohexanol to produce value added chemicals such as 2-cyclohexyl resorcinol, 4-cyclohexyl resorcinol and 3-Hydroxy cyclohexyl phenyl ether under liquid phase reaction condition. TPA/ZrO2 catalysts prepared with different TPA loadings (5-30 wt.%) by wet impregnation method and calcined in the temperature range of 650-850 °C were characterized by Nitrogen sorption analysis, XRD, FTIR, DTG and DTA, and 31P MAS NMR spectroscopy. Among the catalysts studied, 15 wt.%TPA/ZrO2 catalyst calcined at 750 °C gave the highest conversion of resorcinol (51.2%) with the selectivities for 3-Hydroxy cyclohexyl phenyl ether (53.9%) and 2-cyclohexyl resorcinol and 4-cyclohexyl resorcinol together (46.1%) under optimum reaction conditions. However, the selectivity of the products were controlled by varying the reaction conditions. At higher conversion of resorcinol (78.9%), only C-alkylated products were formed at 200 °C with 15 wt.%TPA/ZrO2 catalyst calcined at 750 °C. The combination of TPA and ZrO2 coupled with calcination temperature offered an excellent platform for the conversion of resorcinol into O- or C-alkylated products.

Effect of 'water induced thermogenesis' on body weight, body mass index and body composition of overweight subjects.

CONTEXT: Drinking lots of water is commonly suggested as a part of weight loss regimens. However, only few systematic studies have addressed this notion. In this study, the effect of drinking 1500 ml of water, over and above the daily water intake on body weight, body mass index (BMI) and body composition of overweight subjects was assessed. AIM: To evaluate the role of drinking excessive water in weight reduction and body fat reduction of overweight subjects. SETTINGS AND DESIGN: This study was conducted on 50 overweight girls for eight weeks, during which they were instructed to drink 500 ml of water, three times a day, half an hour before breakfast, lunch and dinner, which was over and above their daily water intake. MATERIAL AND METHODS: Body weight was measured in kilograms (kgs). BMI was calculated as weight in kilograms, which was divided by the square of height in metres. Body composition score was calculated as a sum of skin fold thickness in millimetres at three different sites, which was measured by using skin fold calipers. Pre and post-study body weight, body mass index and body composition scores were measured. STATISTICAL ANALYSIS: SPSS, version 14.0.1 and paired t-test were used to find out the statistical significance of the results. RESULTS: The mean values of the pre-study and post-study body weight, body mass index and body composition scores were 65.86 kg and 64.42 kg, 26.7002 and 26.1224 and 79.626 mm and 76.578 mm respectively. All the three results were highly significant statistically. CONCLUSIONS: The decrease in body weight, body mass index and body composition scores of overweight subjects at the end of study period establishes the role of water induced thermogenesis in weight reduction of overweight subjects.

Re-dispersion and film formation of GdVO4 : Ln3+ (Ln3+ = Dy3+, Eu3+, Sm3+, Tm3+) nanoparticles: particle size and luminescence studies.

GdVO(4) : Ln(3+) (Ln(3+) = Dy(3+), Eu(3+), Sm(3+), Tm(3+)) nanoparticles are prepared by a simple chemical route at 140 °C. The crystallite size can be tuned by varying the pH of the reaction medium. Interestingly, the crystallite size is found to increase significantly when pH increases from 6 to 12. This is related to slower nucleation of the GdVO(4) formation with increase of VO(4)(3-) present in solution. The luminescence study shows an efficient energy transfer from vanadate absorption of GdVO(4) to Ln(3+) and thereby enhanced emissions are obtained. A possible reaction mechanism at different pH values is suggested in this study. As-prepared samples are well dispersed in ethanol, methanol and water, and can be incorporated into polymer films. Luminescence and its decay lifetime studies confirm the decrease in non-radiative transition probability with the increase of heat treatment temperature. Re-dispersed particles will be useful in potential applications of life science and the film will be useful in display devices.

Nanocrystalline HoCrO4: facile synthesis and magnetic properties.

Nanocrystalline HoCrO4 powder was synthesized by a combustion technique using glycine and citric acid as the fuels in different oxidant-to-fuel ratios. Fuel-deficient glycine-nitrate combustion reaction resulted in zircon type HoCrO4 free from HoCrO3 phase. The crystallite size for the phase pure product after calcination at 575 degrees C in oxygen atmosphere was found to be 34 nm by X-ray line broadening. The TEM observations showed highly porous structure. Magnetic measurements reveal the ferromagnetic nature of HoCrO4 nano particles with Tc = 18 K. The compound shows high remanence of 30.4 emu x g(-1) and low coercivity of -0.0343 T.

Luminescence properties of SnO2 nanoparticles dispersed in Eu3+ doped SiO2 matrix.

SnO2 nanoparticles dispersed in Eu3+ doped silica (SnO2-SiO2:Eu3+) were prepared at a low temperature (185 degrees C) in ethylene glycol medium. Transmission electron microscopy studies on as-prepared samples have established that SnO2 nanoparticles having size of 4.6 nm are uniformly covered by the SiO2 matrix. Significant extent of exciton mediated energy transfer between SnO2 and Eu3+ ions in heat treated SnO2-SiO2:Eu3+ samples has been attributed to the diffusion of Eu3+ ions from the SiO2 matrix to the near vicinity of SnO2 nanoparticles and its incorporation in the SnO2 matrix. On the other hand, very weak energy transfer exists for SnO2:Eu3+ nanoparticles heated at different temperatures due to the phase segregation of Eu3+ ions from the matrix.

Experimental and theoretical studies suggesting the possibility of metallic boron nitride edges in porous nanourchins.

We first describe the synthesis of novel and highly porous boron nitride (BN) nanospheres (100-400 nm o.d.) that exhibit a rough surface consisting of open BN nanocones and corrugated BN ribbons. The material was produced by reacting B2O3 with nanoporous carbon spheres under nitrogen at ca. 1750 degrees C. The BN nanospheres were characterized using scanning electron microscopy, high-resolution electron microscopy, and electron energy loss spectroscopy. The porous BN spheres show relatively large surface areas of ca. 290 m2/g and exhibit surprisingly stable field emission properties at low turn-on voltages (e.g., 1-1.3 V/microm). We attribute these outstanding electron emission properties to the presence of finite BN ribbons located at the surface of the nanospheres (exhibiting zigzag edges), which behave like metals as confirmed by first-principles calculations. In addition, our ab initio theoretical results indicate that the work function associated to these zigzag BN ribbons is 1.3 eV lower when compared with BN-bulk material.

Luminescence studies on low temperature synthesized ZnGa2O4:Ln3+ (Ln = Tb and Eu) nanoparticles.

ZnGa2O4 nanoparticles doped with lanthanide ions (Tb3+ and Eu3+) were prepared at a low temperature of 120 degrees C based on urea hydrolysis in ethylene glycol medium. X-ray diffraction studies have confirmed that strain associated with nanoparticles changes as Tb3+ gets incorporated in the ZnGa2O4 lattice. Based on steady state emission and excitation studies of ZnGa2O4:Tb nanoparticles, it has been inferred that ZnGa2O4 host is characterized by a broad emission around 427 nm and there exists energy transfer between the host and Tb3+ ions. Unlike this, for ZnGa2O4:Eu nanoparticles, very poor energy transfer between the host and Eu3+ ions is observed. These nanoparticles when coated with ligands like oleic acid results in their improved dispersion in organic solvents like chloroform and dichloromethane.

Visible light active photocatalytic degradation of bisphenol-A using nitrogen doped TiO2.

Nitrogen doped titania was prepared by low temperature sol-gel method using titanium precursor and nitrogen containing bases like triethylamine and tetramethyl ammonium hydroxide compounds. The materials were characterized by XRD, BET, SEM, XPS, DRS-UV, and FT-IR techniques. DRS-UV study substantially indicates shift of the absorption edge of TiO2 to lower energy region. The phase composition, crystallinity, specific surface area, and visible light activity of nitrogen doped titania depend upon the preparation conditions. Photocatalytic degradation of bisphenol-A in aqueous medium was investigated by TiO2 and nitrogen doped TiO2 under visible light irradiation in a batch photocatalytic reactor. The results indicate higher visible light activity for nitrogen doped TiO2 than commercial TiO2 (Degussa P25) for bisphenol-A degradation. The influence of various parameters such as initial concentration of bisphenol-A, catalyst loading and pH was examined for maximum degradation efficiency.

Preparation and catalytic performances of ultralarge-pore TiSBA-15 mesoporous molecular sieves with very high Ti content.

Highly ordered TiSBA-15 mesoporous molecular sieves with different nSi/nTi ratios and tunable pore diameters have been prepared through direct synthesis under various hydrochloric acid concentrations and synthetic temperatures. The structure and the textural parameters of the materials were investigated by powder X-ray diffraction and nitrogen adsorption/desorption measurements. Decrease of the acid concentration and nSi/nTi ratio in the synthetic gel enhanced the amount of Ti incorporation in SBA-15 materials without affecting their structural order and textural parameters. Highly ordered mesoporous TiSBA-15 with a very high Ti content up to a nSi/nTi ratio of 1.9 was prepared for the first time under the optimized synthesis conditions. Control of synthetic temperature resulted in tuning of pore geometries without structural deterioration and Ti content. Ultralarge-pore TiSBA-15 with a pore size of 12.6 nm and a pore volume of 1.3 cm3 g-1 was also synthesized. The nature and the coordination of the Ti atoms in SBA-15 prepared under various synthesis conditions were investigated by UV-vis spectroscopy. It has been found that the Ti atoms are well-dispersed and mostly occupy the tetrahedral coordination under the optimized synthesis conditions. Catalytic performance of the obtained TiSBA-15 materials was also investigated through oxidation of styrene by hydrogen peroxide and tert-butylhydroperoxide as oxidants.

Direct synthesis and catalytic evaluation of AlSBA-1.

The direct synthesis of the new mesoporous molecular sieve AlSBA-1 containing exclusively tetrahedrally coordinated aluminium and the catalytic activity of the novel material in the isomerization of n-decane are reported.