**Abstract**

Gel polymer electrolyte films (GPEs) based on polyacrylonitrile (PAN) complexed with NaF salt and an Al2O3 nanofiller were prepared via solution cast method. Structural studies were performed to investigate the order of conductivity under the influence of salt and nanofillers. The prepared films were characterized using energy dispersive x-ray spectrometry (EDS) to determine the chemical composition in wt%. EDS studies reveal that PAN–NaF with Al2O3 ceramic filler decreases the degree of crystallinity with increasing concentration of the nanofiller. The UV–Vis spectrum was recorded by a Hewlett-Packard HP8452A diode array spectrometer. The structural effect of salt and nanoparticles on the conductivity was also confirmed by UV–Vis spectroscopy. The mechanical properties of the prepared polymer electrolytes were determined using a Universal Tensile Machine (Instron Model 5565, Canada) with a constant crosshead speed of 10 mm/min. The addition of nanoparticles increased both the modulus and the strength of the polymer nanocomposites. Both the tensile strength and Young's modulus increased with increasing functionalized nanoparticle loading. The change in transition temperature caused by the incorporation of the Al2O3 nanofiller and plasticizer into the PAN+NaF complex was studied by differential scanning calorimetry (DSC) analysis. Additionally, DSC thermograms were recorded to measure the glass transition temperature and melting temperature of PAN-based electrolytes using a Mettler instrument. Conductivity studies were carried out for all the prepared polymer electrolytes to understand the conduction mechanism. The role of the ceramic phase is to reduce the melting temperature, which is ascertained from DSC. The sample containing PAN:NaF (70:30) exhibits the highest conductivity of 1.82 x 10−4 S cm−1 at room temperature (303 K) and 2.96 x 10−3 S cm−1 at 378 K. The polymer electrolytes considered in the present study exhibited an Arrhenius type of conduction. The polymer electrolyte containing 3 wt% Al2O3 nanofiller showed an ionic conductivity of 5.96 × 10−3 S cm−1. To determine transfer numbers, Wagner's polarization method can be used. From these studies, it is observed that the conduction mechanism is predominantly due to ions. Using this (PAN–NaF– Al2O3) (70:30:3) electrolyte, a solid-state electrochemical cell was fabricated, and its discharge profiles were studied under a constant load of 100 kΩ. Finally, several cell profiles associated with this cell were evaluated and reported.

**Keywords:** gel polymer electrolyte, solution casting technique, EDS, UV–vis method, tensile strength, solid-state battery discharge characteristics


*5.2. Information-Disclosing Effect*

Second, we explored whether the MSER affected innovation through the informationdisclosing effect by examining the decrease in information asymmetry. Information asymmetry usually indicates an unpredictable, complex, and volatile transaction environment, which increases transaction costs and hinders firms' innovation activities [15,21]. Thus, the reduction in information asymmetry may prompt innovation. Previous studies have also demonstrated similar results. For example, ref. [14] found that transparency (i.e., low information asymmetry) directly boosted innovation by reducing the sensitivity of management turnover to poor innovative output, and ref. [13] revealed that the more transparent the information environment, the higher the rate of R&D and patenting. At the same time, non-financial reporting for the treatment firms after the MSER were implemented, supplementary to normal financial reports, may have reduced the information asymmetry between the internal managers and outside stakeholders [22,46], thereby improving innovation outputs. To test this conjecture, we followed [22] by using the analyst forecast accuracy (*forecast error*) to measure the firms' information asymmetry. We used the analyst forecast error as an inverse measure of the forecast accuracy, which is defined as the average of the absolute errors of all forecasts made in the year for the target earnings scaled by the stock price at the beginning of the year. If the treatment firms' information asymmetry decreases, we should observe a significant decline in the forecast errors for these firms. Column 2 in Table 8 presents an insignificant coefficient for the analyst forecast accuracy. This observation indicates that the information asymmetry of the treatment firms did not increase after the regulations. Thus, we find the evidence to be inconsistent with this mechanism.


**5. Case study: neem tree**

### **5.1 An overview**

Neem (*Azadirachta indica*) is a common tree throughout Sahel, for a worthy reason. It grows dynamically under semi-arid and humid tropical conditions as well as responds to numerous needs. Its dispersed canopy provides shade from the tropical sun. In the Sahel region, neem tree of many uses including as source of fire wood, it protects millet, sorghum and other crops from desert wind and insect pests as it possessed insecticidal properties, and myriads of medicinal importance. Neems in the Sahel region of both Nigeria and Niger do lacked some minerals in certain period in a year; this resulted to yellowish leaves and stunted growth in the end, appeared unhealthy. Many trees have died due to the lack of those vital

#### *Noteworthy Threatened Plant Species in the Sahel Region, Nigeria DOI: http://dx.doi.org/10.5772/intechopen.93975*

minerals [6]. Moreover, Neem trees are attractive broad-leaved evergreens that can grow up to 30 m tall and 2.5 m in girth. Their dispersal divisions' form rounded crown as much as 20 m across. They continue in leaf except during life-threatening drought, when the leaves may fall off. The short, usually straight trunk has a moderately thick, strongly furrowed bark. The roots enter the soil deeply, at least where the site permits, and, particularly when injured, they produce suckers. This suckering has a habit of to be especially prolific in dry localities. Neem can take significant abuse. For example, it easily withstands pollarding and its topped trunk resprout robustly. The small, white, bisexual flowers are borne in axillary clusters. They attract many bees for honey. Neem honey happened to be popular, and in fact contains no trace of azadirachtin. The fruit is up to 2 cm long, when developed, it became yellow or greenish yellow and comprised a sweet pulp enfolding a seed. It is the kernel that was used most in pest control (The leaves also contain pesticidal ingredients, but as a rule they are much less effective than those of the seed). A neem tree normally start bearing fruit after 3-5 years, became fully productive in 10 years' time and from then, can yield up to 50 kg of fruits annually. It may live for more than two centuries [6].


**Nomenclature**

**References**

111-116

**127**:614-622

**31**

[1] Poulikakos D, Kazmierczak M. Forced convection in a duct partially filled with a porous material. Journal of Heat Transfer. 1987;**109**:653-662

[2] Vafai K, Kim SJ. Forced convection in a channel filled with a porous medium: An exact solution. Journal of Heat Transfer. 1989;**111**:1103-1106

*DOI: http://dx.doi.org/10.5772/intechopen.83482*

local thermal non-equilibrium conditions for thermal transport in metal foams. International Journal of Thermal Sciences. 2015;**95**:73-87

[10] Lu W, Zhao CY, Tassou SA. Thermal analysis on metal-foam filled heat exchangers. Part I: Metal-foam filled pipes. International Journal of Heat and Mass Transfer. 2006;**49**:

[11] Zhao CY, Lu W, Tassou SA. Thermal analysis on metal-foam filled heat exchangers. Part II: Tube heat exchangers. International Journal of Heat and Mass Transfer. 2006;**49**:

[12] Ouyang XL, Vafai K, Jiang PX. Analysis of thermally developing flow in porous media under local thermal nonequilibrium conditions. International Journal of Heat and Mass Transfer.

[13] Xu HJ, Zhao CY, Xu ZG. Analytical considerations of slip flow and heat transfer through microfoams in mini/ microchannels with asymmetric wall

[14] Shaikh AW, Memon GQ. Analytical and numerical solutions of fluid flow filled with and without porous media in circular pipes. Applied Mathematics and

heat fluxes. Applied Thermal Engineering. 2016;**93**:15-26

Computation. 2014;**232**:983-999

Liquids. 2018;**254**:446-462

[15] Sheikholeslami M, Houman BR. CVFEM for effect of Lorentz forces on nanofluid flow in a porous complex shaped enclosure by means of nonequilibrium model. Journal of Molecular

[16] Hassan M. Impact of iron oxide particles concentration under a highly oscillating magnetic field on ferrofluid

2751-2761

*Measurement of Heat and Mass Flow Characteristics of Nanofluid in a Porous Parallel-Plate…*

2762-2770

2013;**67**:768-775

[3] Gong W, Han J, Cheng F. Theoretical study of heat transfer enhancement in pipe with porous body. Journal of Hydrodynamics, Series B. 2001;**13**:

[4] Cheng P, Hsu CT. Fully-developed, forced convective flow through an annular packed-sphere bed with wall effects. International Journal of Heat and Mass Transfer. 1986;**29**:1843-1853

[5] Mitrovic J, Maletic B. Effect of thermal asymmetry on laminar forced convection heat transfer in a porous annular channel. Chemical Engineering and Technology. 2006;**29**:750-760

[6] Sheikholeslami M, Shahzad SA, Li Z, Ahmad S. Numerical modeling for

[7] Sheikholeslami M. CuO-water nanofluid free convection in a porous cavity considering Darcy law. European Physical Journal Plus. 2017;**132**:55-66

[8] Kuznetsov AV. Analysis of a nonthermal equilibrium fluid flow in a concentric tube annulus filled with a porous medium. International Communications in Heat and Mass

[9] Xu HJ, Gong L, Zhao CY, Yang YH, Xu ZG. Analytical considerations of

Transfer. 1996;**23**:929-938

alumina nanofluid magnetohydrodynamic convective heat transfer in a permeable medium using Darcy law. International Journal of Heat and Mass Transfer. 2018;

*A* specific surface area


*3.1. Anti-Cancer Therapy*

Recently, numerous studies have reported that biodegradable polymeric nanocarriers possess a superior stealth function for the detection of the reticuloendothelial system in the human body and exhibit an enhanced permeability and retention effect [56–61]. In particular, these polymeric nanoparticles are capable of having several beneficial properties, such as biomimetics, stimuli-sensitivity, easy modification, and exquisite target specificity compared to carriers composed of other materials. These advantages support the possibility that stereocomplex nanoparticles can be used as a promising approach in the field of anticancer therapy.

Goldberg proposed that oligomers of PDLA were used for the formation of stereocomplex crystals with L-lactate in the human body to induce lactate deficiency in cancer cells [62]. This study suggested that tumor growth could be inhibited and terminated by stereocomplexation through lactate deficiency to retain the electrical neutrality of tumors. In preliminary experiments, it was demonstrated that high concentrations of PDLA could induce stereocomplexation with lactate in the body, which exhibited cytotoxic effects on the tumor. Li et al. (2016) fabricated sc-PLA-coated nanoparticles with multiple functionalities for a highly tunable drug delivery system via simple LbL self-assembly [14]. TEM images show that the nanoparticles had a spherical shape with a core–shell structure and a diameter of approximately 190 nm (Figure 12b). The in vitro drug release profiles of doxorubicin (DOX)-loaded nanoparticles were analyzed at different pH and temperature conditions to demonstrate the ability to adjust the drug delivery of the sc-PLA-coated nanoparticles. As shown in Figure 12c, the drug release rate was significantly reduced with increasing pH from 3.5 to 7.4. The cumulative release of DOX was 73.1 vs. 55.6% at pH 3.5 and 7.4 after 12 h, respectively. This is because acidic conditions could stimulate protonation of the tertiary amine groups in the outermost layer of the sc-PLA-coated nanoparticles, resulting in the swelling of nanoparticles. Furthermore, a lower pH yields the nanoparticles pHresponsive properties through an increase in the solubility of DOX, which retains phenols and amines. In addition to pH, the cumulative release of DOX was 39.8 vs. 60% at 37 and 20 ◦C after 12 h, respectively. A lower temperature condition could facilitate a more rapid release via swelling of the outer layer of sc-PLA-coated nanoparticles. Consequently, the nanoparticles based on sc-PLA could tune the rate and amount of drug release, depending on the physiological conditions. To identify the cytotoxicity of DOX-loaded sc-PLA-coated nanoparticles to breast cancer cells, MCF-7 cells were incubated with free DOX and two types of DOX-loaded sc-PLA nanoparticles (Figure 12d). During the incubation of cancer cells with free DOX, most of the DOXs were localized in the cell nuclei, instead of the cytoplasm. In contrast, the DOXs released from all sc-PLA particles infiltrated the cells, and their accumulation was significantly increased. These results indicated that sc-PLAcoated nanoparticles could effectively act as anti-cancer drug carriers by improving the cell uptake efficiency.

**Figure 12.** (**a**) Schematic representation for highly tunable sc-PLA coated nanoparticles and drug delivery. (**b**) TEM image of Fe3O4@SiO2@SC-N nanoparticles. Scale bar: 200 nm. (**c**) In vitro drug release profiles of DOX-loaded Fe3O4@SiO2@SC-D nanoparticles in acidic condition of pH 3.5 (A), physiological condition of pH 7.4 (B), and Fe3O4@SiO2@SC-N nanoparticles at 20 ◦C (C) and 37 ◦C (D). (**d**) Confocal laser scanning microscope observations of MCF-7 cells incubated with free DOX (**i**), DOX-loaded Fe3O4@SiO2@SC-N (**ii**), and Fe3O4@SiO2@SC-D (**iii**) nanoparticles. Each panel named DIC, DAPI, Dox, and Merged depicts a differential interference contrast (DIC) image, cell nuclei staining by DAPI, DOX fluorescence in cells, and overlay of the all images, respectively. (iv) Comparison of fluorescence intensity in three specimens calculated by ImageJ [14], Copyright 2015. Reproduced with permission from the American Chemical Society.

Brzezi ´nski et al. synthesized DOX-loaded stereocomplexed microspheres using spontaneous precipitation after the polymerization of L-proline-functionalized PLLA and PDLA via coordination polymerization (Figure 13a) [63]. Therein, the size of the microparticles was dependent on whether the L-proline end groups were blocked or unblocked in the microspheres. Based on this correlation, they obtained spherical microspheres with various sizes ranging from 0.5 to 10 μm through adjusting the solvent and functionalization. In the in vitro release profiles of DOX, stereocomplexed microspheres with Boc-protected L-proline exhibited cumulative release within 10% of loaded contents for 100 h, while microspheres with unblocked L-proline showed a faster cumulative release of 41–81% of loaded contents for the same duration (Figure 13b). This can be attributed to the low surface area of the Boc-protected group, which delayed hydrolysis. In contrast, the unblocked group could easily release DOX due to the localization of DOX on the surface of the microsphere, resulting in an initial burst release. To evaluate the cytotoxicity of the DOX-loaded stereocomplexed microspheres, A549 lung cancer cells were incubated with medium extracts of the two types of microspheres. Figure 13b shows a very slow reduction in the cell viability of cancer cells cultured with Boc-protected microspheres after 24 h, whereas the cell viability of the cancer cells cultured with unblocked microspheres was dramatically decreased after incubation for 2 h and decreased to below 25% after 24 h. This

can be attributed to the difference in drug release rate between the blocked and unblocked microspheres. In particular, the microspheres prepared in tetrahydrofuran (THF) showed a significantly high anti-proliferative effect.

**Figure 13.** (**a**) Synthesis process of Boc-L-proline functionalized PLLA and PDLA, unblocking of L-proline end groups (top). Schematic illustration for fabrication of sc-PLA microspheres using spontaneous precipitation from mixture of enantiomeric PLAs (bottom). (**b**) In vitro release profiles of DOX from sc-PLA microspheres functionalized with (**i**) Boc-L-proline and (**ii**) L-proline. In vitro cytotoxicity test on A459 cells incubated with medium extracts of the sc-PLA microspheres functionalized with (**iii**) Boc-L-proline and (**iv**) L-proline at incubation times of 2, 6, and 24 h [63], Copyright 2019. Reproduced with permission from Elsevier B.V.

In addition, Brzezi ´nski et al. successfully fabricated stereocomplexed micelles with β-cyclodextrin (β-CD) core as an intracellular drug carrier [64]. Hence, micelles stability can be improved, and in vitro release rate of DOX from supramolecular nanocarriers can be controlled. The stereocomplexed micelles with DOX efficiently inhibited the proliferation of HeLa (cervical cancer) and K562 (chronic myelogenous leukemia). This study suggested that the supramolecular interactions facilitate effective establishment of drug delivery system as an anti-cancer therapy.