Determination of Optimal Electrospinning Distance and Applied Voltage for Polyacrylonitrile Electrospun Fibre Production

Electrospinning process is highly dictated by electric field strength. Thus, two key parameters i.e., electrospinning distance and applied voltage, determine the quality of electrospun fibres. Incorrect selection of these parameters will result in poor fibre qualities. There ought to be an optimal combination of electrospinning distance and applied voltage to produce best quality fibres from a given material. In this study, the optimal combination of electrospinning distance and applied voltage was assessed based on consistency of electrospinning process, amount of fibre, fibre morphology, and average fibre diameter. Polyacrylonitrile (PAN) electrospun fibre samples were prepared at different combinations of electrospinning distance and applied voltage. Scanning electron microscopy and image analysis were conducted to assess the quality and average diameter of the fibres. The results indicate that for electrospinning of PAN, the distance should be between 10 and 20 cm with a 15 to 20 kV of applied voltages. Findings from this study is crucial for producing optimal fibre quality in PAN electrospun nanofibre synthesis

T Cells Enhance Stem-Like Properties and Conditional Malignancy in Gliomas

Small populations of highly tumorigenic stem-like cells (cancer stem cells; CSCs) can exist within, and uniquely regenerate cancers including malignant brain tumors (gliomas). Many aspects of glioma CSCs (GSCs), however, have been characterized in non-physiological settings.We found gene expression similarity superiorly defined glioma "stemness", and revealed that GSC similarity increased with lower tumor grade. Using this method, we examined stemness in human grade IV gliomas (GBM) before and after dendritic cell (DC) vaccine therapy. This was followed by gene expression, phenotypic and functional analysis of murine GL26 tumors recovered from nude, wild-type, or DC-vaccinated host brains.GSC similarity was specifically increased in post-vaccine GBMs, and correlated best to vaccine-altered gene expression and endogenous anti-tumor T cell activity. GL26 analysis confirmed immune alterations, specific acquisition of stem cell markers, specifically enhanced sensitivity to anti-stem drug (cyclopamine), and enhanced tumorigenicity in wild-type hosts, in tumors in proportion to anti-tumor T cell activity. Nevertheless, vaccine-exposed GL26 cells were no more tumorigenic than parental GL26 in T cell-deficient hosts, though they otherwise appeared similar to GSCs enriched by chemotherapy. Finally, vaccine-exposed GBM and GL26 exhibited relatively homogeneous expression of genes expressed in progenitor cells and/or differentiation.T cell activity represents an inducible physiological process capable of proportionally enriching GSCs in human and mouse gliomas. Stem-like gliomas enriched by strong T cell activity, however, may differ from other GSCs in that their stem-like properties may be disassociated from increased tumor malignancy and heterogeneity under specific host immune conditions

Analysis of the effectiveness of brake insulator in decreasing the brake squeal noise

Brake functions when two different materials are in contact to reduce a motion. Due to surface irregularity, this contact at high revolution and contact force produces irritating noise called brake squeal. This paper presents the study of introducing brake insulator into the brake assembly in order to reduce the noise. Different configurations of insulators are used in the Finite Element Analysis (FEA). The effectiveness of the brake insulator is analyzed using different type of materials. The finite element model of the brake is developed based on actual drum brake dimensions. FEA is used to for modal analysis to predict the modal frequencies and mode shapes. Various friction coefficients, wheel speeds and brake forces are considered in the analysis. The squeal is shown by positive real part of the baseline graph. The accompanied slip rate in the baseline model of the insulator increases the brake squeal noise significantly

Product design improvement Of water dispenser tap using TRIZ method

To produce the best solution for improving any product design that should be able to satisfy the design requirements (i.e.,faster better and cheaper), there were several stages typically involves the root cause analysis and idea generation activities. In this paper, product design improvement of a water dispenser is demonstrated using Theory of Inventive Problem Solving (TRIZ) method. The objective of this study was to find out the design solution which was able to solve the problem of water spill out that occurred after dispensing water from the dispenser tap. TRIZ Function Model and Engineering Contradiction method were used to model the problem, followed by TRIZ Contradiction Matrix and 40 Inventive Principles to generate potential solutions. The design improvement process based on the TRIZ method generated new concept design of water dispenser tap component which was able to eliminate the water spill out problem, while maintaining the existing dispensing function. In addition, the new dispenser tap conceptual design also required less component to operate compared with the existing design, hence, lowering the product cost

Fabrication of Superhydrophobic Polyacrylonitrile (PAN) nanofibres membranes for membrane distillation technology

Membrane distillation (MD) is a promising water desalination technology that is capable of treating high salinity water. However, the problematic fouling issues and membrane wetting are the primary impediments to the large-scale application of this technology. To overcome the mentioned problems, the distilling membrane should be made from anti-wetting materials and possess a highly porous structure. In this study, a superhydrophobic nanofibrous membrane was fabricated through surface coating of electrospun polyacrylonitrile (PAN) nanofibres membranes using silica nanoparticles and fluorinated alkyl silane surface treatment. The coated PAN nanofibre membranes were characterised using scanning electron microscope (SEM), water contact angle (WCA) method, Fourier transform infrared (FTIR) and differential scanning calorimetry (DSC). It was observed that the amount and size of silica nanoparticle were related to hydrolysis time, which was crucial in determining the membrane pore size and formation of superhydrophobic surface. The presence of silica nanoparticles and fluorine content significantly improved the hydrophobicity and thermal properties of the nanofibres. The results from this study provide valuable insights into the understanding of the behaviour of silica nanoparticles and the method to fabricate superhydrophobic electrospun nanofibre membranes for MD application

Determination of optimal electrospinning distance and applied voltage for polyacrylonitrile electrospun fibre production

Electrospinning process is highly dictated by electric field strength. Thus, two key parameters i.e., electrospinning distance and applied voltage, determine the quality of electrospun fibres. Incorrect selection of these parameters will result in poor fibre qualities. There ought to be an optimal combination of electrospinning distance and applied voltage to produce best quality fibres from a given material. In this study, the optimal combination of electrospinning distance and applied voltage was assessed based on consistency of electrospinning process, amount of fibre, fibre morphology, and average fibre diameter. Polyacrylonitrile (PAN) electrospun fibre samples were prepared at different combinations of electrospinning distance and applied voltage. Scanning electron microscopy and image analysis were conducted to assess the quality and average diameter of the fibres. The results indicate that for electrospinning of PAN, the distance should be between 10 and 20 cm with a 15 to 20 kV of applied voltages. Findings from this study is crucial for producing optimal fibre quality in PAN electrospun nanofibre synthesis