title: Green and economic fabrication of Zinc Oxide (ZnO) Nanorods as a broadband UV blocker and antimicrobial agent

authors: Taghizadeh, Seyedeh-Masoumeh

subjects: Science & Technology

abstract: Zinc oxide (ZnO) nanoparticles have gained widespread interest due to their unique properties, making them suitable for a range of applications. Several methods for their production are available, and of these, controlled synthesis techniques are particularly favourable. Large-scale culturing of Chlorella vulgaris produces secretory carbohydrates as a waste product, which have been shown to play an important role in directing the particle size and morphology of nanoparticles. In this investigation, ZnO nanorods were produced through a controlled synthesis approach using secretory carbohydrates from C. vulgaris, which presents a cost-effective and sustainable alternative to the existing techniques. Fourier transform infrared (FTIR) spectroscopy, X-ray powder diffraction (XRD) analysis, transmission electron microscopy (TEM), and UV-Vis spectroscopy were used to characterise the nanorods. The prepared nanorods exhibited a broad range of UV absorption, which suggests that the particles are a promising broadband sun blocker and are likely to be effective for the fabrication of sunscreens with protection against both UVB (290–320 nm) and UVA (320–400 nm) radiations. The antimicrobial activity of the prepared nanorods against Gram-positive and Gram-negative bacteria was also assessed. The nanostructures had a crystalline structure and rod-like appearance, with an average length and width of 150 nm and 21 nm, respectively. The nanorods also demonstrated notable antibacterial activity, and 250 μg/mL was determined to be the most effective concentration. The antibacterial properties of the ZnO nanorods suggest its suitability for a range of antimicrobial uses, such as in the food industry and for various biomedical applications

text: Green and economic fabrication of Zinc Oxide (ZnO) Nanorods as a broadband UV blocker and antimicrobial agent Zinc oxide (ZnO) nanoparticles have gained widespread interest due to their unique properties, making them suitable for a range of applications. Several methods for their production are available, and of these, controlled synthesis techniques are particularly favourable. Large-scale culturing of Chlorella vulgaris produces secretory carbohydrates as a waste product, which have been shown to play an important role in directing the particle size and morphology of nanoparticles. In this investigation, ZnO nanorods were produced through a controlled synthesis approach using secretory carbohydrates from C. vulgaris, which presents a cost-effective and sustainable alternative to the existing techniques. Fourier transform infrared (FTIR) spectroscopy, X-ray powder diffraction (XRD) analysis, transmission electron microscopy (TEM), and UV-Vis spectroscopy were used to characterise the nanorods. The prepared nanorods exhibited a broad range of UV absorption, which suggests that the particles are a promising broadband sun blocker and are likely to be effective for the fabrication of sunscreens with protection against both UVB (290–320 nm) and UVA (320–400 nm) radiations. The antimicrobial activity of the prepared nanorods against Gram-positive and Gram-negative bacteria was also assessed. The nanostructures had a crystalline structure and rod-like appearance, with an average length and width of 150 nm and 21 nm, respectively. The nanorods also demonstrated notable antibacterial activity, and 250 μg/mL was determined to be the most effective concentration. The antibacterial properties of the ZnO nanorods suggest its suitability for a range of antimicrobial uses, such as in the food industry and for various biomedical applications

year: 2020

title: Crystal structure of pyruvate decarboxylase from Zymobacter palmae

authors: Buddrus, Lisa

subjects: Science & Technology

abstract: Pyruvate decarboxylase (PDC; EC 4.1.1.1) is a thiamine pyrophosphate- and Mg²⁺ ion-dependent enzyme that catalyses the non-oxidative decarboxylation of pyruvate to acetaldehyde and carbon dioxide. It is rare in bacteria, but is a key enzyme in homofermentative metabolism, where ethanol is the major product. Here, the previously unreported crystal structure of the bacterial pyruvate decarboxylase from Zymobacter palmae is presented. The crystals were shown to diffract to 2.15 Å resolution. They belonged to space group P21, with unit-cell parameters a = 204.56, b = 177.39, c = 244.55 Å and Rᵣ.ᵢ.ₘ. = 0.175 (0.714 in the highest resolution bin). The structure was solved by molecular replacement using PDB entry 2vbi as a model and the final R values were Rwₒᵣₖ = 0.186 (0.271 in the highest resolution bin) and Rfᵣₑₑ = 0.220 (0.300 in the highest resolution bin). Each of the six tetramers is a dimer of dimers, with each monomer sharing its thiamine pyrophosphate across the dimer interface, and some contain ethylene glycol mimicking the substrate pyruvate in the active site. Comparison with other bacterial PDCs shows a correlation of higher thermostability with greater tetramer interface area and number of interactions.

text: Crystal structure of pyruvate decarboxylase from Zymobacter palmae Pyruvate decarboxylase (PDC; EC 4.1.1.1) is a thiamine pyrophosphate- and Mg²⁺ ion-dependent enzyme that catalyses the non-oxidative decarboxylation of pyruvate to acetaldehyde and carbon dioxide. It is rare in bacteria, but is a key enzyme in homofermentative metabolism, where ethanol is the major product. Here, the previously unreported crystal structure of the bacterial pyruvate decarboxylase from Zymobacter palmae is presented. The crystals were shown to diffract to 2.15 Å resolution. They belonged to space group P21, with unit-cell parameters a = 204.56, b = 177.39, c = 244.55 Å and Rᵣ.ᵢ.ₘ. = 0.175 (0.714 in the highest resolution bin). The structure was solved by molecular replacement using PDB entry 2vbi as a model and the final R values were Rwₒᵣₖ = 0.186 (0.271 in the highest resolution bin) and Rfᵣₑₑ = 0.220 (0.300 in the highest resolution bin). Each of the six tetramers is a dimer of dimers, with each monomer sharing its thiamine pyrophosphate across the dimer interface, and some contain ethylene glycol mimicking the substrate pyruvate in the active site. Comparison with other bacterial PDCs shows a correlation of higher thermostability with greater tetramer interface area and number of interactions.

year: 2016

title: The Te Kotahitanga Observation Tool: Development, use, reliability and validity.

authors: Berryman, Mere

subjects: chool reform

abstract: Te Kotahitanga is a New Zealand school reform project aimed at improving the pedagogical contexts in mainstream classrooms in which the indigenous Māori students have traditionally been marginalised. It does this by assisting teachers to implement an Effective Teaching Profile. Part of this process uses an observation tool to monitor the degree to which participating teachers are incorporating the interactions and relationships described in the Effective Teaching Profile into their day-to-day teaching. Given the central importance of these tasks, the Te Kotahitanga team undertook to test the observation tool for measurement reliability and validity. In order to undertake this study, the team conducted synchronous observations amongst trainers (the Professional Development Coordinator and Regional Coordinators) to ascertain their level of consistency when using the tool. The team then conducted synchronous observations between trainers and 38 in-school facilitators in the 12 schools involved in Phase 3 of the project. In total 41 teachers were observed and over 200 Māori students were involved in these observations. This study suggests that the tool can produce consistent and reliable results when observers have been effectively trained.

text: The Te Kotahitanga Observation Tool: Development, use, reliability and validity. Te Kotahitanga is a New Zealand school reform project aimed at improving the pedagogical contexts in mainstream classrooms in which the indigenous Māori students have traditionally been marginalised. It does this by assisting teachers to implement an Effective Teaching Profile. Part of this process uses an observation tool to monitor the degree to which participating teachers are incorporating the interactions and relationships described in the Effective Teaching Profile into their day-to-day teaching. Given the central importance of these tasks, the Te Kotahitanga team undertook to test the observation tool for measurement reliability and validity. In order to undertake this study, the team conducted synchronous observations amongst trainers (the Professional Development Coordinator and Regional Coordinators) to ascertain their level of consistency when using the tool. The team then conducted synchronous observations between trainers and 38 in-school facilitators in the 12 schools involved in Phase 3 of the project. In total 41 teachers were observed and over 200 Māori students were involved in these observations. This study suggests that the tool can produce consistent and reliable results when observers have been effectively trained.

year: 2011