The effect of a self-pulsing non-equilibrium plasma discharge on piezoelectric PVDF nanofiber membrane was investigated. The plasma discharge was generated in air with a DC power source, with a ...discharge current of 0.012 mA, a nominal interelectrode separation of 1 mm, and discharge voltage of ~970 V. In a continuous fabrication process, the electrospinning method was used to generate thin nanofiber membrane with a flow rate of 0.7–1 mL h−1 and 25–27 kV voltage to obtain the nanofiber with high sensitivity and a higher degree of alignment and uniformity over a larger area. Plasma treatment was applied on both single layer and multi-layer (three layers) nanomembranes. In addition, simultaneously, the nanofiber membranes were heat-treated at a glass transition temperature (80–120 °C) and then underwent plasma treatment. Fourier-transform infrared (FTIR) spectroscopy showed that the area under the curve at 840 and 1272 cm−1 (β phase) increased due to the application of plasma and differential scanning calorimeter (DSC) indicated an increase in the degree of crystallinity. Finally, PVDF sensors were fabricated from the nanofibers and their piezoelectric properties were characterized. The results suggested that compared to the pristine samples the piezoelectric properties in the plasma and plasma-heat-treated sensors were enhanced by 70% and 85% respectively.
In this work, we report the effect of steady-state atmospheric plasma (Corona discharge) in nanofibers and nanocomposite membranes for piezoelectric applications. The investigation was performed in ...PVDF (Poly vinylidene fluoride) nanofibers, CNT (Carbon Nanotubes)-reinforced PVDF nanocomposites, and PAN (Poly acrylonitrile) nanofiber membranes. Steady-state plasma was generated with a high voltage power source with 1 mA discharge current output and 6 kV discharge voltage, and the gap between tip and the material was maintained to be 1 cm. For the fabrication of nanofibers and nanocomposite membranes, an electrospinning method was used. The electrospinning parameters, such as flow rate and voltage, were optimally tuned for obtaining uniform nanofibers and nanomembranes. Along with the plasma treatment, heat treatment above the glass transition temperature was also conducted on the nanofiber membranes. Using a Scanning Electron Microscope (SEM), the morphology of the nanofibers was observed. X-ray Diffraction (XRD) demonstrated the polycrystallinity of the nanofibers. Fourier Transform Infrared Spectroscopy (FTIR) analysis of the PVDF nanofibers shows a peak at 796 cm
representing α-phase (C-H rocking) in the control sample which is absent in the treated samples. Raman spectroscopy of PVDF nanofibers identifies a Raman shift from 873 cm
to 877 cm
(denoting β-phase) for plasma-treated samples only. Electron Paramagnetic Resonance (EPR) concludes that the intensity of the free radicals increases from 1.37 to 1.46 (a.u.) after plasma treatment. Then, sensors were fabricated from the PVDF nanofibers, MWCNT-reinforced PVDF nanofibers, and PAN nanofibers to characterize their piezoelectric properties. The impact test results showed that the atmospheric plasma and heat-treated samples had 86%, 277%, and 92% increases of the d
value (piezoelectric coefficient) in the case of PVDF nanofibers, MWCNT-reinforced nanofibers, and PAN nanofibers, respectively. It was also observed that the capacitance of the nanofiber membranes has increased due to the plasma treatment.
Background
There is growing potential for nanocarrier-based drug delivery in cancer. However, an incomplete understanding of nano–bio interactions and the challenges regarding processing and ...fabrication in scale-up engineering techniques, controls over drug release, efficacy, and cytotoxicity to the human cell are the major challenges for its clinical success. The purpose of the study was to develop an electrospraying processing of injectable nanonized encapsulated chemotherapeutics to target primary and metastatic breast cancer tumor microenvironment for precise and controlled delivery.
Results
A novel coaxial electrospraying of multiple cancer drugs (paclitaxel and GW2580) as core and polycaprolactam (PCL) as the shell has been developed to produce multi-cancer drug nanocapsules. Using electrospraying process, we have successfully made nanocapsules containing paclitaxel to target breast cancer cells and GW2580, a colony-stimulating factor 1 receptor (CSF1R) inhibitor to target CSF1R+ myeloid cells in the tumor microenvironments (TME). The UV–vis drug release test for 14 days shows a prolonged and sustained release pattern of both the drugs. In vitro and in vivo results showed the effects of nanocapsules containing multiple drugs in controlling the growth of tumor cells and increased survival of the animal bearing breast cancers.
Conclusion
Nanonized multi-cancer drugs were encapsulated in a PCL shell. The drug doses ratio and the polymer-to-drug ratio were controlled by engineered process parameters. The studies showed the importance of making nanocapsules containing nanocrystals of multiple drugs, which will pave the way of making multiple drug combinations in a controlled manner and capsules can be designed for sustained release of the drugs after accumulation into the TME. TME-directed therapy can be a norm in future cancer treatment strategies. These injectable nanocapsules will allow cancer site-specific precision and controlled delivery to cure primary and metastatic breast cancer and to overcome the chemotherapy resistance.
We report a phenomenal increase in strength, modulus, and fracture strain of ultra high molecular weight polyethylene (UHMWPE) fiber by 103 %, 219 %, and 108 %, respectively through hybridizing this ...fiber with Nylon 6 as a minor phase and simultaneously reinforcing it with single-walled carbon nanotubes (SWCNTs). Loading of Nylon 6 and SWCNTs into UHMWPE was 20.0 wt% and 2.0 wt%, respectively. Hybridized fibers were processed using a solution spinning method coupled with melt mixing and extrusion. We claim that the enhancement in strain-to-failure of the nanocomposites is due to induced plasticity in the hybridized Nylon 6-UHMWPE polymers. The enhancement in strength and stiffness in the nanocomposites is attributed to the load sharing of the SWCNTs during deformation. Differential scanning calorimetry (DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) studies showed that changes in percent crystallinity, rate of crystallization, crystallite size, alignment of nanotubes, sliding of polymer interfaces and strong adhesion of CNT/polymer blends were responsible for such enhancements.
Hybrid nanocomposite fibers from a blend of Ultrahigh molecular weight polyethylene (UHM-WPE)+Nylon-6+single-walled carbon nanotubes (SWCNT) were produced using a solution spinning process, both with ...and without a compatibilizer, Polyethylene-graft-Maleic Anhydride (PEG-
g
-MAH). The loading of Nylon-6, PE-
g
-MAH and SWCNTs was 20, 3, and 2 wt% of UHMWPE. A comparative morphological study of the fibers was performed using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR) analysis. SEM images of hybrid fiber cross-sections have shown polymer-coated SWCNTs aligned along the direction of extrusion inside the polymer. The blends with compatibilizer have shown rough and indistinct interfacial separation of the constituent phases, as seen in both cross-sectional and longitudinal views of fibers in SEM micrographs. Whereas, the samples without compatibilizer showed distinct minor polymer phase as droplets. DSC results indicate reduction of crystallinity, crystallization rate and lamellar size in the compatibilized blends. Comparative FTIR analysis of the fiber blends showed the presence of new absorbance peaks (at 1753.62 and 1210–990 cm
–1
) suggesting formation of imide linkages between the UHMWPE backbone and Nylon-6 chains in the blends with compatibilizer via reactive functional groups present in the PE-
g
-MAH. The appearance of these peaks were more prominent when nanotubes were present in the blend.
Ultrahigh molecular weight polyethylene (PE) filaments were reinforced with 2 wt.% of single-walled carbon nanotubes (SWCNTs). The solution spinning method was used to produce both neat and ...reinforced PE filaments. Tensile tests and strain hardening through repeated loading-unloading cycles of the filaments revealed a spectacular contribution of the SWCNTs in enhancing the elastic properties, e.g., strength and modulus. The theoretic strength and modulus of the reinforced PE were predicted using the shear lag model and micromechanics-based model, respectively, and verifying with experimental results. It was observed that the predicted strength and modulus were comparable only with those obtained after strain hardening. In the next step, a molecular dynamic simulation was conducted by simulating a unit cell containing a SWCNT surrounded by PE matrix subjected to uniaxial tensile strain. The strength and modulus of the simulated structure showed an agreement, to certain extent, with experimental observations of strain-hardened nanocomposites.
Although it is obvious that chemical pesticides may have adverse effects on health and the environment, farmers in our nation frequently use chemical pesticides in crop fields to manage pests. This ...research work focuses on analyzing farmers’ attitudes towards chemical pesticide application. Using a prepared questionnaire, the study was carried out in several Chapainawabganj sites, and information was gathered from 50 randomly chosen farmers. Appropriate scales were developed to measure the variables. Descriptive statistics, such as mean, standard deviation, range, and percentage, were used to characterize the variables. According to the findings, the bulk of the respondents in the research area was old aged 46%. The findings also reveal that 54% of the respondents do not have a primary school education, 62% of the respondents have a medium-sized farm, 52% of the respondents have high annual income, 90% of the respondents do not have organizational training and 84% of the total respondents have high farming experience of crop cultivation. The study indicates that 76% of respondents had medium knowledge of pesticide application and the use of pesticides was viewed with a moderate attitude by 76% of the respondents. In this study, we find a positive significant relationship between farmers’ knowledge about chemical pesticides and the use of pesticides. Besides, there is also another positive significant relationship between extension media contact and the use of pesticides. Farmers in the research region were found to be more likely to use chemical pesticides to increase productivity by controlling pest attacks. Therefore, the current study could subsidize improving better guidelines aim at applying fewer pesticides in the crop field and improving farmers’ knowledge of the balanced use of pesticides. The extension service providers might educate farmers on the responsible use of chemical pesticides, raise their level of knowledge on the control of insects, and provide alternative ways for insect pest management in the research area.
We have investigated strain hardening behavior of ultrahigh molecular weight polyethylene (UHMWPE) reinforced with 2.0 wt% loading of multiwalled carbon nanotubes (MWCNTs). A solution spinning ...process was used to produce neat and MWCNT-reinforced filaments of UHMWPE. Tensile tests of filaments showed 62% and 114% improvement in strength and modulus, respectively. Strain hardening tests on filaments revealed spectacular contribution by MWCNTs in enhancing strength and modulus by more than one order of magnitude. SEM micrographs showed sufficient coating of nanotube surface with the polymer that promoted interface adhesion. This intimate interfacial interaction enforced alignment of nanotubes during repeated loading-unloading sequences and allowed effective load transfer to nanotubes. Close interaction between UHMWPE and nanotubes was further evidenced by Raman spectral distribution as a positive shift in the D-band suggesting compressive stress on nanotubes by lateral compression of polymer. Nanotubes thus deformed induced the desired strain hardening ability in the UHMWPE filament. Differential scanning calorimetry (DSC) tests indicated around 15% increase in crystallinity after strain hardening—which together with nanotube alignment resulted in such dramatic improvement in properties.
Cellulose acetate (CA) fibers were reinforced with multi-walled carbon nanotubes (MWCNTs) at 0.5%, 1.0%, 1.5% and 2.0%. Yield strength, ultimate tensile strength, fracture strain and toughness of the ...nanocomposite fiber increased up to 1.5 wt. % of the carbon nanotube (CNT) loading, however, further inclusion (2.0%) of MWCNTs in CA decreased the mechanical properties. Experimental properties were also compared with analytical predictions using a Shear lag model for strength and the rule of mixture for modulus. A solution spinning process, coupled with sonication, mixing, and extrusion, was used to process the CNT-reinforced composite fiber. Scanning electron microscopy (SEM) images of the cross sections of neat CA and CA-MWCNT fibers showed the formation of voids and irregular features. The enhanced interconnected fibrillation in the CNT-reinforced CA samples resulted in improved mechanical properties, which were observed by tensile testing. Fourier transform infrared spectroscopy (FTIR) spectra showed the area under the curve for C–H bonding after the inclusion of CNT. There was no significant shift of wavenumber for the inclusion of MWCNT in the CA matrix, which indicates that the sonication process of the CNT-loaded solution did not degrade the CA bonding structure.
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