Polyvinylpyrrolidone (PVP)/cellulose acetate (CA) composite nanofibres loaded with Chromolaena odorata (L) King extract were prepared using the electrospinning method. The physicochemical properties ...of nanofibre composites, including their morphology, size, crystallinity, chemical interactions and compressive strength, were studied. In vitro tests including antioxidant, antibacterial and release activities were also investigated. The morphology of the nanofibre composites containing C. odorata extract (COE) had a smooth, homogeneous and flexible surface and fibres with a diameter of 1454 nm. Fourier-transform infrared spectroscopy analysis showed the interaction of PVP, CA and COE molecules through hydrogen bonds. The XRD pattern showed that crystals were transformed into the amorphous state when COE was converted into nanocomposite fibres. The Young's modulus values of the resulting nanofibre composites were in the range of 199–209 MPa. The antioxidant activity of PVP/CA nanocomposite fibres contained higher COE than did pure COE, whereas the antibacterial activity of PVP/CA/COE nanofibre was as strong as that of pure COE. The release rate of COE in nanofibres increases faster than does pure COE.
Utilizing carbon materials derived from natural biomass holds significant promise for battery applications, owing to their low cost, abundant availability, and environmentally sustainable ...characteristics. However, graphite anode materials do not meet the demands of efficient batteries. Coconut shell waste has the potential to be used as activated carbon in energy storage anodes. By adding silicon dioxide (SiO2) to maintain structural stability and electrochemical reaction kinetics, the advantages of CCS can be maximized. Polyacrylonitrile/polyvinylidene fluoride (PAN/PVDF) composite polymer was used as a matrix to embed CCS/SiO2 and synthesize nanofibers via electrospinning. The resulting nanofibers had diameters ranging from to 575–707 nm, with cross-linked, porous, and beadless characteristics. Mechanical properties were measured by single-fiber micro tensile tests. The young modulus, tensile strength, and toughness of each nanofiber were successfully maintained at 13.7 ± 0.4 MPa, 34.4 ± 0.1 MPa, and 982 ± 10 kJ/m3, respectively, because of the presence of a β-crystal growth layer that facilitated efficient stress transmission. The reduction-oxidation process response had a potential difference of less than 1.286 V in the first cycle, whereas for the third and fifth cycles, it was maintained below 3.416 V. The lithium-ion diffusion coefficient was below 4.73×1013 cm2/s. Using the anode directly, as in lithium-ion batteries, provided a high capacity of 382 mAh/g after 200 cycles. Good cycle stability, with over 98% retention of the initial capacitance after 200 charge/discharge cycles, underscores its potential for application in lithium-ion batteries.
Polyvinylidene fluoride (PVDF) is hydrophobic, piezoelectric, and has good chemical stability and high mechanical properties; therefore, it is often used to reinforce other composite materials for ...various applications. However, the characteristics of pure PVDF nanofibers have rarely been comprehensively explored. This study prepared pure PVDF nanofiber membranes using electrospinning and investigated their physicochemical and mechanical properties. Scanning electron microscopy revealed that the PVDF nanofiber surfaces were white, homogeneous, flat, bead-free, and smooth, and that the nanofiber diameters were 230–855 nm. Fourier-transform infrared analyses showed that the β phase was dominant in all the nanofibers. The spectra showed that the α, β, and γ phases were present in PVDF1 and PVDF2, whereas PVDF3 and PVDF4 were dominated by the β and γ phases. The PVDF nanofiber samples had a semi-crystalline structure with crystallinity values of 58.45–52.67%. The tensile strength of the PVDF nanofibers increased from 3.61 to 6.00 MPa with an increasing PVDF concentration. The application of a high voltage during the electrospinning process did not damage the chemical structure of the PVDF nanofibers. The PVDF nanofiber membranes produced in this study are potential candidates for application in wound healing, water filtration, and masks.
Increasing concentrations of PVDF affect the physicochemical and mechanical properties of PVDF nanofibres, which improve the morphology and tensile strength of PVDF nanofiber membranes. Moreover, an increasing concentration of PVDF influences the nanofiber crystallization process, with the typical β phase being the dominant. Display omitted
Abstract
This research was aimed to develop a valid and practical Students’ Worksheet of Natural Science for junior high school students based on critical thinking skills. The development model used ...in this research was the Rowntree development model consisting of three steps, namely planning, development, and evaluation. The evaluation step was the formative evaluation step by Tessmer consisted of five steps, namely self-evaluation, expert review, one-to-one evaluation, small-group evaluation, and field testing. However, the field testing step was not done because the research objectives were only focused on validity and practicality. The data had been collected using walkthrough and questionnaire techniques. The results showed that the developed product was in a highly valid category based on the score of expert validations. The validation score obtained from the language expert was 4.73, the score obtained from the design expert was 4.56, and the validation score of critical thinking skills was 4.56. At the one-to-one evaluation step, the product was declared as very practical, practical, and quite practical. At the small-group evaluation step, the product was declared very practical and practical. Thus, the developed product has been valid and practical.
Energy storage and modern electronics industries are in essential need of high dielectric and highly flexible materials. In this study, polyacrylonitrile and reduced graphene oxide (PAN/GO) were ...prepared by electrospinning. The composite morphology produced a homogeneous, smooth, and flexible surface with high tensile strength and durability. The diameter of the fibers in the composite mats ranged from 232 to 592 nm. The X-ray diffraction pattern recording displayed a sharp peak characteristic centered between 20 and 30° angles with a maximum degree of crystallinity of 86.23%. The evaluation of the Fourier-transform infrared spectrum indicated the interaction between GO and PAN through hydrogen bonds. The differential scanning calorimetry measurements confirmed that GO acted as a nucleating agent that improves the thermal stability of the composite. The dielectric properties exhibited the relative permittivity of the composite of 86.4 with a dielectric loss (tan δ) of 4.97 at 102 Hz, and the maximum conductivity was achieved at 34.9 × 10–6 Sm–1 at high frequencies.
Graphene oxide derived from palm kernel shells (rGOPKS) and polyacrylonitrile (PAN) were electrospun into composite fiber mats and evaluated as supercapacitor electrode materials. Their morphologies ...and crystalline properties were examined, and chemical interactions between rGOPKS and PAN were investigated. The diameters of individual fibers in the rGOPKS/PAN composite mats ranged from 1.351 to 1506 μm and increased with increasing rGOPKS content. A broad peak centered near 23° in the X-ray diffraction (XRD) pattern of rGOPKS corresponded to the (002) planes in graphitic carbon. Characteristic rGOPKS and PAN peaks were observed in the XRD patterns of all the composite fibers, and their Fourier-transform infrared (FTIR) spectra indicated hydrogen bond formation between rGOPKS and PAN. The composite fiber mats had smooth and homogeneous surfaces, and they exhibited excellent flexibility and durability. Their electrochemical performance as electrodes was assessed, and a maximum specific capacitance of 203 F g
−1
was achieved. The cycling stability of this electrode was excellent, and it retained over 90% of its capacitance after 5000 cycles. The electrode had an energy density of 17 W h kg
−1
at a power density of 3000 W kg
−1
. Dielectric results showed a nanofiber composite dielectric constant of 72.3 with minor leakage current (tan
δ
)
i.e.
, 0.33 at 51 Hz. These results indicate that the rGOPKS/PAN composite fibers have great promise as supercapacitor electrode materials.
Graphene oxide derived from palm kernel shells (rGOPKS) and polyacrylonitrile (PAN) were electrospun into composite fiber mats and evaluated as supercapacitor electrode materials.
A lot of skin care products sold in the market shows us that skin care is an important part of lifestyle for both women and men. Considering that everyone has different skin profle, a recommendation ...system is required to help and give a personalised suggestion products based on the user's preferences. Recommendation system provides suggestions that effciently narrowing down the amount of informations so users will directed to the items which is most suitable for their skin. The method used in this paper is Content Based Filtering with K-means clustering for suggestion product calculation. The result is the system that can recommend skin care products for the users based on products they like, thus the users would fnd products those possibly suitable for their skin.
Polyvinylpyrrolidone (PVP) is among the most extensively used polymer in electrospinning. It has excellent electrospinnabibilty, aqueous solubility, and biocompatibility. PVP has demonstrated ...potential application as drug delivery matrix and wound dressing material. However, PVP is easily degraded in the presence of moisture/water. Incorporation of cellulose acetate (CA) in PVP nanofiber is a promising way to increase of resistance to water. The objective of this study was to prepare to PVP/CA nanofiber by electrospinning method and to determine their characteristics. The SEM result shows that electrospinning of PVP/CA solution at 5% concentration (FC1) resulted in beaded fiber. At 10% (FC2) and 15% (FC3) concentration, the resulted PVP/CA fibers were bead-free. The average diameter of FC1-, FC2-, and FC3 were 258, 398, 534 nm, respectively. The FTIR analysis confirmed the presence of PVP and CA in FC1-, FC2- and FC3 nanofiber as indicated by characteristic peaks of hydroxyl groups and cyclic amides (PVP); and alkane and carboxyl groups (CA). The XRD study revealed amorphous state of PVP nanofiber and crystallinity state of CA nanofiber. The mechanical test showed that electrospun fiber with smaller diameter had greater tensile strength. The presence of CA increased the functional properties of PVP-based nanofiber.
One of the museum's functions is to communicate museum collections to the public, usually by museum tour guides. Given the limited number of guide and the ability of the guide to reach all visitors ...when the museum is crowded, the researcher attempts to create an innovation to support the role of the guide, which provides information collection of museums easily and quickly accessed by visitor through a mobile-based application, based on visitor characteristics. The output from the research is a mobile-based application that provides access to information services museum collections that visitors can use, which obtained SUS score of 68.9 or value of "Good" and fall into the above-average category.
This study reports the experimental results of the measurement and analysis of the moment of inertia (MOI) of rigid bodies using a smartphone magnetometer. The MOI apparatus comprises a spiral ...spring, stand, deviation scale, and vibration counter. The magnetometer application used on the smartphone is the Physics Toolbox Sensor Suite. The magnet, which is placed on top of the MOI apparatus, rotates with the rigid body, and the smartphone magnetometer is used to detect the magnetic field values. We experimentally determine the relationship between the magnetic field and time. The time function is used to analyse the oscillation period of the rigid bodies, which comprise a solid cylinder, solid sphere, solid cone, and solid circular disc. The oscillation periods are proportional to the radii of the rigid bodies. This experience will trigger student interest in conducting related experiments.
PDF
