**4.4. Algorithm classification**

The final image is classified by the method of detection modes and valleys of the histogram. The classification algorithm implemented is summarized by the following steps:

The details of the third point of this classification algorithm can be found in (Akono et al., 2003).


**4.3 Laparoscopic adjustable gastric banding (LAGB)-gut microbiota**

To our knowledge gut microbiota changes, have not been studied after LAGB surgery [53].

#### **4.4 Biliopancreatic diversion (BPD)-gut microbiota**

BPD/DS rats have significantly different microbiota than SHAM animals. Decreased gut microbiota richness and diversity were observed in BPD/DS rats. Microbial profile analysis showed a major shift from presurgical Clostridialesdominated microbiota to high-concentration microbiota in *Bifidobacteriales* soon after surgery. After BPD/SD, the gut is divided into three functional segments: the alimentary limb, biliopancreatic limb, and common limb. *Bifidobacteriales* have a high content in the alimentary limb and common limb. But because the biliopancreatic limb contains a significant amount of *Actinomycetales*, it is different from the other two limbs. In BPD/DS, unlike RYGB, it was shown that *Bifidobacteriales* elevated significantly as represented by the increasing abundance of *the Bifidobacterium* genus. In the lower part of the intestine, the presence of nutrients, which is digestible, but undigested can change the microbiota. In BPD/ SD rats, changes in the gut microbiota were associated with the beneficial influence of malabsorption procedures. Increasing the proportion of *Bifidobacteriales* bacteria associated with the genus *Bifidobacterium* may have health benefits for the host. *Bifidobacterium* predominance in the microbiota can reduce low-grade inflammation. The positive outcomes of surgery may be because of gut microbiota modulation and more specifically increase in *Bifidobacterium* abundance throughout the gastrointestinal tract [54].


**4. Classification of adsorptive bubble separation method and classification**

### **4.1 Collectors and mechanism of action**

When the particles of interest (colligend) do not have surface active properties of their own, they are made effective surface active or collected by adding to the collectors in an adsorptive bubble separation process. Ionic surfactant travels to the surface of gas bubbles increasing through the liquid during ion flotation, and the surface becomes charged [8]. The oppositely charged substance of interest (Colligend) adsorbs to the bubble interface as a counter ion, forming an electrical double layer. Because of the foam's high surface area to liquid volume ratio, the liquid that emerges from its breakdown is much more concentrated in the ion than the original solution. The colligend should be specific for the interface of a charged surfactant. Surfactant molecules have two parts: one is hydrophobic, while the other is hydrophilic. The hydrophilic portion comes outside, while the hydrophobic part stays within. The hydrophilic component was applied to the substance of interest and taken away at the foam bubble interface (**Figure 1**).

Enantiomeric mixtures are separated using chiral collectors. These chiral molecules are known to interact with analytes in a variety of ways, including ligand exchanged interactions, hydrophobic inclusion complexation, and hydrogenbonding interactions. Colligend must be used as a foaming agent so chiral collectors are not foaming agents. Enantioselectivity can be caused by a disparity in the chiral collector's and two enantiomers' reaction mechanism.

**Figure 1.**

*Classification of adsorptive bubble separation method classification.*


**3. Experimental**

#### *3.1. Fuel Sample and Char Preparation*

The raw material used in this work is abundantly available lignite from the Rhenish area, which was pre-processed and pre-dried for the use in a 2300 MWth lignite power plant. The pre-drying was performed via a fluidized bed with internal waste heat utilization [19]. The ultimate and proximate analysis of the fuel sample is shown in Table 1. The mean Sauter diameter of the sample is about 140 μm.

**Table 1.** Proximate and ultimate analyses of the char samples, oxygen calculated by difference.

The chars for the TGA experiments were prepared by devolatilizing the raw fuels in a muffle furnace at 900 ◦C for 7 min according to DIN 51720 or ISO 562:2010, respectively. Generally, the kinetics of the gasification strongly depend on the duration of the pyrolysis and the temperature gradient used during the heat up [20]. Devolatilizing the samples according to DIN 51720 leads to significantly higher heating rates than any possible pyrolysis in the TGA, but still is slower than heating rates one can expect in a fluidized bed gasifier.


**8. Corrosion behavior of Pb-free nano-composite solder joints**

This author has recently worked on the development of nano-composite solders in microelectronic packaging by applying two methods of fabrication: mechanical mixing of inert nano-particles (Fig. 10) and precipitation of nano-IMC in the solder matrix (Fig. 11) [57]. The average size of the nominally spherical nano-Al2O3 particles was 100 nm in diameter.

Notably, the addition of nano-particles decreased the size of dendrite β-Sn grains, the needle-like Ag3Sn grains, and Ag3Sn phase located between the average spacing. When 1 wt% was added, the superfine spherical nano-Ag3Sn grains were about 0.16 ± 0.06μm in length and 0.15 ± 0.05 μm in diameter, and the average spacing between them was a significant improvement (0.14 ± 0.05μm), significantly smaller than the sizes found in the SAC composite solder. However, large Ag3Sn IMCs were not observed in the Pb-free SAC solder. Another, author reported that the effects of nano-TiO2 particles on the interfacial microstructures and bonding strength of Sn3.5Ag0.5Cu nano-composite solder joints in ball grid array (BGA) packages with immersion Sn surface finishes [58]. It is clearly shown in Fig. 12a, b that the discontinuous Cu6Sn5 IMC layer grows with a rough scallop shape (Mark A), and wicker-Cu6Sn5 IMC forms on the rough scallop-shaped Cu6Sn5 IMC layer (Mark B) and grows into the SAC solder matrix. However, the addition of a small percentage of nano-TiO2 particles alters the Pb-free Sn3.5Ag0.5Cu composite solder/pad interface morphology after reflowing, as shown in the SEM micrographs in Fig. 12c, d. Only the continuous scallop-shaped Cu6Sn5 IMC layer was detected at the interface. However, the wicker-Cu6Sn5 IMC disappeared at the interface with the Cu pads. In addition, the number of Ag3Sn IMC forms increased in the eutectic area when the content of nano- TiO2 particles was increased to 0.25–1 wt%. It is interesting that the smallest

Corrosion Resistance of Pb-Free and

composite solder[57].

Novel Nano-Composite Solders in Electronic Packaging 121

Fig. 11. SEM image of the (a) Sn3.5Ag0.5Cu solder and (b) Sn3.5Ag0.5Cu -1TiO2 nano-

thickness of the IMC layer was achieved with the addition of 1 wt% of nano-TiO2 particles. The thickness of the Cu6Sn5 IMC layer was reduced by 51%. The results indicate that the growth of the Cu6Sn5 IMC layer at the solder/pad interfaces of Sn3.5Ag0.5Cu is depressed through the small addition of nano-TiO2 particles[58]. With the addition of 0.5– 1 wt% nano-TiO2 particles, fracture occurred in all of the solder joints as cracks propagated through the Sn3.5Ag0.5Cu composite solder balls, which ruptured mostly along the submicro Ag3Sn IMC and solder matrix, as shown in Fig. 13a, b. This phenomenon is similar to that occurring in Pb-free Sn0.7Cu composite solder BGA packages[59].

Fig. 10. The nano-Al2O3 particles used in this study: (a) FE-SEM micrograph, and (b) X-ray diffraction spectrum[57].

thickness of the IMC layer was achieved with the addition of 1 wt% of nano-TiO2 particles. The thickness of the Cu6Sn5 IMC layer was reduced by 51%. The results indicate that the growth of the Cu6Sn5 IMC layer at the solder/pad interfaces of Sn3.5Ag0.5Cu is depressed through the small addition of nano-TiO2 particles[58]. With the addition of 0.5– 1 wt% nano-TiO2 particles, fracture occurred in all of the solder joints as cracks propagated through the Sn3.5Ag0.5Cu composite solder balls, which ruptured mostly along the submicro Ag3Sn IMC and solder matrix, as shown in Fig. 13a, b. This phenomenon is similar to that occurring in Pb-free Sn0.7Cu composite solder BGA

Fig. 10. The nano-Al2O3 particles used in this study: (a) FE-SEM micrograph, and (b) X-ray

packages[59].

diffraction spectrum[57].

Fig. 11. SEM image of the (a) Sn3.5Ag0.5Cu solder and (b) Sn3.5Ag0.5Cu -1TiO2 nanocomposite solder[57].

Corrosion Resistance of Pb-Free and

packages after ball shear tests [58].

Novel Nano-Composite Solders in Electronic Packaging 123

Fig. 13. Fractography of the Sn3.5Ag0.5Cu-1TiO2 nano-composite solder joints in BGA

To achieve high reliability, solder materials must have high resistance to corrosive conditions such as moisture, air pollutants from industry, and oceanic environments[54]. Although corrosion of solder alloys is not currently a major problem for electronic devices used in normal environments, it may be a problem when they are used in harsh environments, such as oceanic environments. However, there is a lack of information regarding the corrosion resistance of nano-composite solders in corrosive environments.

Figure 14 shows the polarization curves of the Sn3.5Ag0.5Cu solder and the Sn3.5Ag0.5Cu nano-composite solder in 3.5 wt.% NaCl solution[60]. From the polarization curves, the corrosion potential (*Φ*corr), the breakdown potential (*Φ*b), and the dynamic corrosion current density (*I*corr) have been determined (Table 6). The width of the passive region on the anodic polarization curves (Δ*Φ* = *Φ*b - *Φ*corr) in Table 6 indicates the pitting

Fig. 12. Morphology of intermetallic compounds formed at the interfaces of the as-reflowed solder joints: (a) Sn3.5Ag0.5Cu, ( b) (a) magnifications ; (c) d Sn3.5Ag0.5Cu-0.75TiO2; (d) (c) magnifications [58].

Fig. 12. Morphology of intermetallic compounds formed at the interfaces of the as-reflowed solder joints: (a) Sn3.5Ag0.5Cu, ( b) (a) magnifications ; (c) d Sn3.5Ag0.5Cu-0.75TiO2; (d) (c)

magnifications [58].

Fig. 13. Fractography of the Sn3.5Ag0.5Cu-1TiO2 nano-composite solder joints in BGA packages after ball shear tests [58].

To achieve high reliability, solder materials must have high resistance to corrosive conditions such as moisture, air pollutants from industry, and oceanic environments[54]. Although corrosion of solder alloys is not currently a major problem for electronic devices used in normal environments, it may be a problem when they are used in harsh environments, such as oceanic environments. However, there is a lack of information regarding the corrosion resistance of nano-composite solders in corrosive environments.

Figure 14 shows the polarization curves of the Sn3.5Ag0.5Cu solder and the Sn3.5Ag0.5Cu nano-composite solder in 3.5 wt.% NaCl solution[60]. From the polarization curves, the corrosion potential (*Φ*corr), the breakdown potential (*Φ*b), and the dynamic corrosion current density (*I*corr) have been determined (Table 6). The width of the passive region on the anodic polarization curves (Δ*Φ* = *Φ*b - *Φ*corr) in Table 6 indicates the pitting

Corrosion Resistance of Pb-Free and

Solder

Sn3.5Ag0.5Cu-0.5TiO2

polarization tests[60].

0.5Al2O3 [60].

Novel Nano-Composite Solders in Electronic Packaging 125

Sn3.5Ag0.5Cu All area 69.26 4.05 0.37 13.40 12.60

flake 72.97 0.43 - 15.71 9.58

mushroom 74.87 1.29 - 17.97 5.76

flake 64.22 0.50 15.03 20.25

Table 7. Surface element concentration of different solders after potentiodynamic

Fig. 14. The potentiodynamic polarization curves of the nano-composite solder in a 3.5wt.% NaCl solution: (a) Sn3.5Ag0.5Cu solder; (b) Sn3.5Ag0.5Cu-0.5TiO2; and (c) Sn3.5Ag0.5Cu-

All area 68.7 3.82 0.68 13.39 13.41

Surface element concentration (wt.%)

Sn Ag Cu Cl O

resistibility or the stability of the passive film on the Sn3.5Ag0.5Cu composite alloy surface. The corrosion potential (*Φ*corr) of the Sn3.5Ag0.5Cu nano-composite solder is slightly more passive than that of the Sn3.5Ag0.5Cu solder. This implies that a finer grain size produces more grain *b*oundaries, which act as corrosion barriers. On the other hand, the breakdown potential (*Φ*b) of the Sn3.5Ag0.5Cu nano-composite solders becomes much more passive with the addition of oxide nanoparticles. As Table 6 also indicates, the Sn3.5Ag0.5Cu solders possess a higher pitting tendency (smaller Δ*Φ* value) than the Sn3.5Ag0.5Cu nano-composite solders. Rosalbino et al. reported that the pit formation at the surface of Sn–Ag–M alloys is due to the dissolution of the tin-rich phase [56]. In addition, the corrosion current densities were obtained by using the TAFEL extrapolation method. The corrosion current densities of the Sn3.5Ag0.5Cu solders and Sn3.5Ag0.5Cu nano-composite solders were very similar.

Φcorr : corrosion potential; Icorr: corrosion current density; Φb : breakdown potential; ΔΦ = Φcorr - Φb.

Table 6. Corrosion properties in a 3.5 wt.% NaCl solution for the nano-composite solder [60].

Many studies have reported that the corrosion behavior of alloys depends on the second phase distribution, shown to be Mg alloy[61, 62] and Al alloy[63]. In the Sn3.5Ag0.Cu nanocomposite solder alloys, the microstructure had finer β-Sn grains, a large amount of Ag3Sn particles, and a small amount of oxidize nanoparticles. This leads to improvement of the corrosion behavior of the Sn3.5Ag0.5Cu nano-composite solder, such as greater corrosion resistance, the lower pitting tendency, and the smaller corrosion current density, respectively.

The corrosion products of Sn3.5Ag0.5Cu and Sn3.5Ag0.5Cu nano-composite solder have similar microstructures (Fig. 15). The corrosion products of Sn3.5Ag0.5Cu solder after polarization have a larger flake-like shape (Mark a) and small mushroom-like shape, and are loosely distributed on the surface, with different orientations (Fig.15a). On the other hand, the corrosion products of Sn3.5Ag0.5Cu nano-composite solder after polarization tests have only a flake-like shape, as shown in Fig. 15b (Mark a). Table 7 shows the surface element concentrations of solder corrosion products from EDS. According to the EDS analysis, the corrosion products of Sn3.5Ag0.5Cu and Sn3.5Ag0.5Cu nano-composite solder contain mainly Sn, O, and Cl (Fig.16). It can be seen that the corrosion products of the Sn3.5Ag0.5Cu solders and Sn3.5Ag0.5Cu nano-composite solders have slightly different compositions.

resistibility or the stability of the passive film on the Sn3.5Ag0.5Cu composite alloy surface. The corrosion potential (*Φ*corr) of the Sn3.5Ag0.5Cu nano-composite solder is slightly more passive than that of the Sn3.5Ag0.5Cu solder. This implies that a finer grain size produces more grain *b*oundaries, which act as corrosion barriers. On the other hand, the breakdown potential (*Φ*b) of the Sn3.5Ag0.5Cu nano-composite solders becomes much more passive with the addition of oxide nanoparticles. As Table 6 also indicates, the Sn3.5Ag0.5Cu solders possess a higher pitting tendency (smaller Δ*Φ* value) than the Sn3.5Ag0.5Cu nano-composite solders. Rosalbino et al. reported that the pit formation at the surface of Sn–Ag–M alloys is due to the dissolution of the tin-rich phase [56]. In addition, the corrosion current densities were obtained by using the TAFEL extrapolation method. The corrosion current densities of the Sn3.5Ag0.5Cu solders and Sn3.5Ag0.5Cu

nano-composite solders were very similar.

ΔΦ = Φcorr - Φb.

respectively.

different compositions.

[60].

Solder *Φ*corr

(mVSCE)

Φcorr : corrosion potential; Icorr: corrosion current density; Φb : breakdown potential;

*Φ*b (mVSCE)

Sn3.5Ag0.5Cu -662.1 -284.1 378 0.36

Sn3.5Ag0.5Cu-0.5TiO2 -651.4 -95.1 556 0.27

Sn3.5Ag0.5Cu-0.5Al2O3 -642.1 -146.2 496 0.40

Table 6. Corrosion properties in a 3.5 wt.% NaCl solution for the nano-composite solder

Many studies have reported that the corrosion behavior of alloys depends on the second phase distribution, shown to be Mg alloy[61, 62] and Al alloy[63]. In the Sn3.5Ag0.Cu nanocomposite solder alloys, the microstructure had finer β-Sn grains, a large amount of Ag3Sn particles, and a small amount of oxidize nanoparticles. This leads to improvement of the corrosion behavior of the Sn3.5Ag0.5Cu nano-composite solder, such as greater corrosion resistance, the lower pitting tendency, and the smaller corrosion current density,

The corrosion products of Sn3.5Ag0.5Cu and Sn3.5Ag0.5Cu nano-composite solder have similar microstructures (Fig. 15). The corrosion products of Sn3.5Ag0.5Cu solder after polarization have a larger flake-like shape (Mark a) and small mushroom-like shape, and are loosely distributed on the surface, with different orientations (Fig.15a). On the other hand, the corrosion products of Sn3.5Ag0.5Cu nano-composite solder after polarization tests have only a flake-like shape, as shown in Fig. 15b (Mark a). Table 7 shows the surface element concentrations of solder corrosion products from EDS. According to the EDS analysis, the corrosion products of Sn3.5Ag0.5Cu and Sn3.5Ag0.5Cu nano-composite solder contain mainly Sn, O, and Cl (Fig.16). It can be seen that the corrosion products of the Sn3.5Ag0.5Cu solders and Sn3.5Ag0.5Cu nano-composite solders have slightly

Δ*Φ* (mV)

*I*corr (μA/cm2)

Table 7. Surface element concentration of different solders after potentiodynamic polarization tests[60].

Fig. 14. The potentiodynamic polarization curves of the nano-composite solder in a 3.5wt.% NaCl solution: (a) Sn3.5Ag0.5Cu solder; (b) Sn3.5Ag0.5Cu-0.5TiO2; and (c) Sn3.5Ag0.5Cu-0.5Al2O3 [60].

Corrosion Resistance of Pb-Free and

reported [46, 64,65]:

the following reaction[66]:

Sn3O(OH)2Cl2.

polarization tests[60].

Novel Nano-Composite Solders in Electronic Packaging 127

The dehydration of Sn(OH)2 and Sn(OH)4 into SnO and SnO2, respectively, has also been

However, Yu et al., after investigating the corrosion properties of Sn9Zn and Sn8Zn3Bi solder in NaCl solution, postulated the formation of a tin oxyhydroxychloride according to

In addition, Li et al.[46] studied the corrosion properties of Sn-Ag, Sn–Ag–Cu, Sn–Cu, and SnPb solder in 3.5wt.% NaCl solution with different scanning rates, and their results showed that the corrosion product on the surface was tin oxide chloride hydroxide (Sn3O(OH)2Cl2). In our case, the presence of such a surface layer, instead of a tin oxychloride layer, cannot be ruled out due to the detection limits of energy-dispersive spectroscopy. In order to understand the reaction during the corrosion products, XRD has been used to analyse the corrosion products on the surface after the polarization tests (Fig. 17). The results show that all the Sn3.5Ag0.5Cu and Sn3.5Ag0.5Cu solder materials have the same corrosion product, Sn3O(OH)2Cl2, which is a complex oxide chloride hydroxide of tin[67]. This further confirms that the corrosion product on the Sn3.5Ag0.5Cu composite solders is

Fig. 16. EDS analysis of corrosion product of the Sn3.5Ag0.5Cu nano-composite solder after

Sn + 2OH� − 2e� = SnO + H�O (4)

Sn + 4H�O = Sn(OH)� + 4e� + 4H� (5)

Sn(OH)� + 2OH� + 2e� = Sn(OH)� (6)

Sn(OH)� + 2OH� = SnO + H�O (7)

SnO + H�O + 2OH� + 2e� = Sn(OH)� (8)

3Sn + 4OH� + 2Cl� = Sn�O(OH)�Cl� + H�O (9)

Fig. 15. Microstructure of the corrosion products on different solders after polarization tests (a) Sn3.5Ag0.5Cu solder, (b) Sn3.5Ag0.5Cu nano-composite solder[60].

During polarization testing in NaCl solution, the only possible cathodic reaction is oxygen reduction [49, 64]:

$$\text{H}\_2\text{O}\_2 + 4\text{e}^- + 2\text{H}\_2 \rightarrow 4\text{OH}^- \tag{1}$$

When the current density reaches about 10 mA/cm2, many hydrogen bubbles evolve from the cathode due to the hydrogen evolution on the cathode:

$$2\text{H}\_2\text{O} + 2\text{e}^- \rightarrow \text{H}\_2 + 2\text{OH}^- \tag{2}$$

The reactions on the anode are quite complicated. Some possible anodic reactions have been reported in the literature [46, 64-66], as displayed below:

$$\text{Sn} + 2\text{OH}^- - 2\text{e}^- = \text{Sn(OH)}\_2 \tag{3}$$

Fig. 15. Microstructure of the corrosion products on different solders after polarization tests

During polarization testing in NaCl solution, the only possible cathodic reaction is oxygen

When the current density reaches about 10 mA/cm2, many hydrogen bubbles evolve from

The reactions on the anode are quite complicated. Some possible anodic reactions have been

O� + 4e� + 2H� → 4OH� (1)

2H�O + 2e� → H� + 2OH� (2)

Sn + 2OH� − 2e� = Sn(OH)� (3)

(a) Sn3.5Ag0.5Cu solder, (b) Sn3.5Ag0.5Cu nano-composite solder[60].

the cathode due to the hydrogen evolution on the cathode:

reported in the literature [46, 64-66], as displayed below:

reduction [49, 64]:

$$\text{Sn} + 2\text{OH}^- - 2\text{e}^- = \text{SnO} + \text{H}\_2\text{O} \tag{4}$$

$$\text{Sn} + 4\text{H}\_2\text{O} = \text{Sn(OH)}\_4 + 4\text{e}^- + 4\text{H}^+ \tag{5}$$

The dehydration of Sn(OH)2 and Sn(OH)4 into SnO and SnO2, respectively, has also been reported [46, 64,65]:

$$\text{Sn(OH)}\_{2} + 2\text{OH}^{-} + 2\text{e}^{-} = \text{Sn(OH)}\_{4} \tag{6}$$

$$\text{Sn(OH)}\_{2} + 2\text{OH}^{-} = \text{SnO} + \text{H}\_{2}\text{O} \tag{7}$$

$$\text{SnO} + \text{H}\_2\text{O} + 2\text{OH}^- + 2\text{e}^- = \text{Sn(OH)}\_4 \tag{8}$$

However, Yu et al., after investigating the corrosion properties of Sn9Zn and Sn8Zn3Bi solder in NaCl solution, postulated the formation of a tin oxyhydroxychloride according to the following reaction[66]:

$$\rm{^2SSn} + 4\rm{OH}^- + 2\rm{Cl}^- = \rm{Sn}\_3\rm{O}(\rm{OH})\_2\rm{Cl}\_2 + \rm{H}\_2\rm{O} \tag{9}$$

In addition, Li et al.[46] studied the corrosion properties of Sn-Ag, Sn–Ag–Cu, Sn–Cu, and SnPb solder in 3.5wt.% NaCl solution with different scanning rates, and their results showed that the corrosion product on the surface was tin oxide chloride hydroxide (Sn3O(OH)2Cl2). In our case, the presence of such a surface layer, instead of a tin oxychloride layer, cannot be ruled out due to the detection limits of energy-dispersive spectroscopy. In order to understand the reaction during the corrosion products, XRD has been used to analyse the corrosion products on the surface after the polarization tests (Fig. 17). The results show that all the Sn3.5Ag0.5Cu and Sn3.5Ag0.5Cu solder materials have the same corrosion product, Sn3O(OH)2Cl2, which is a complex oxide chloride hydroxide of tin[67]. This further confirms that the corrosion product on the Sn3.5Ag0.5Cu composite solders is Sn3O(OH)2Cl2.

Fig. 16. EDS analysis of corrosion product of the Sn3.5Ag0.5Cu nano-composite solder after polarization tests[60].

Corrosion Resistance of Pb-Free and

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(http://www.itrs.net/Links/2009ITRS/2009Chapters\_2009Tables/2009\_Assembly.

[3] S. Jin, D. R. Frear, J.W. Morris Jr. Foreword, J. Electron. Mater. 23 (8) (1994) 709-713. [4] M. Abtew, G. Selvaduray, Lead-free Solders in Microelectronics, Mater. Sci. Eng. R 27

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[53] U. S. Mohanty, K. L. Lin, Electrochemical corrosion behaviour of Pb-free Sn-8.5Zn-

[54] J. Hu, T. Luo, A. Hu, M. Li, D. Mao, Electrochemical Corrosion Behaviors of Sn-9Zn-3BixCr Solder in 3.5% NaCl Solution, J. Electron. Mater. 40, (2011) 1556-1562. [55] T. C. Chang, J. W. Wang, M. C. Wang , M. H. Hon, Solderability of Sn-9Zn-0.5Ag-1In

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[57] T. H. Chuang, M. W. Wu , S. Y. Chang, S. F. Ping, L. C. Tsao, Strengthening mechanism

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0.05Al-XGa and Sn-3Ag-0.5Cu alloys in chloride containing aqueous solution,

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microstructure and bonding strengths of Sn3.5Ag0.5Cu composite solder BGA packages with immersion Sn surface finish, J Mater Sci: Mater Electron, (2011)1443-

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[34] X.Y. Liu, M.L. Huang, C. M. L. Wu, Lai Wang, Effect of Y2O3 particles on microstructure

[35] S. M. L. Nai, J. Wei, M. Gupta, Interfacial Intermetallic Growth and Shear Strength of Lead-Free Composite Solder Joints, J. Alloy Compd. 473 (2009) 100–106. [36] A. K. Gain, T. Fouzder, Y. C. Chan, Winco K. C. Yung, Microstructure, kinetic analysis

[37] R. Ambat, P. Møller, A review of Corrosion and environmental effects on electronics, The Technical University of Denmark, DMS vintermøde proceedings, (2006). [38] M. Mori, K. Miura, Corrosion of Tin Alloys in ulfuric and Nitric Acids, Corrosion

[39] F. Song, S. W. Ricky Lee, Corrosion of Sn-Ag-Cu Lead-free Solders and the

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Interconnects , J. Electron. Mater. 40, 2011,doi: 10.1007/s11664-011-1705-y. [41] Morten S. Jellesen et al., Corrosion in Electronics (Paper presented at 2008 Eurocorr

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**6**

Swe-Kai Chen

*Taiwan*

*National Tsing Hua University, Hsinchu,*

**Electrochemical Passive Properties**

**of AlxCoCrFeNi (x = 0, 0.25, 0.50, 1.00) High-Entropy Alloys in Sulfuric Acids**

*Center for Nanotechnology, Materials Science, and Microsystems (CNMM),*

**1.1 Pseudo-unitary lattice with a characteristic parameter as a description of**

In the summer of 1995, J.W. Yeh and the author (SKC) started the study of multi-principalelement alloys which was called, then, alloys with high randomness and now the high-entropy alloys (HEAs). SKC checked the first 10 equal-molar alloys, which was designed by Yeh that contained from 6 to 9 elements in the alloys out of one of Al, Cu, and Mo, together with Ti, V, Fe, Ni, Zr, Co, Cr, Pd, and B, with a home-made vacuum-arc remelter, and the author observed that the alloy series containing Mo can be made most easily, while the ones containing 3 at% B are the ones most difficult in melting, and 6 out of 10 can be formed in the water-cooled copper mold of the remelter, i.e., the existence of the HEAs was demonstrated by experiments. The alloys were aimed at that time to design as another kind of bulk glass alloys, and based on the high configurational entropy of R ln(n), n between 5 and 13, similar to the mixing of different gases [1]. No conclusions were drawn with XRD patterns of these alloys that were found two years later to be composed with peaks from a single simple lattice cell like FCC A1 or BCC A2, although some evidence of existence of amorphous phase was observed from TEM diffraction patterns and high resolution images [2,3]. The simple crystalline phases instead of amorphous ones were continuously found in alloys like in AlCoCrCuFeNi during research of HEAs in these 10 to 20 years, and identified with a so-called extended FCC or BCC

As multiple principal element alloys, high-entropy alloys (HEAs) comprise at least five elements whose concentration for each one ranges between 5 at % and 35 at % [5]. Attributes of forming a simple solid solution and nano-particle precipitation, as well as achieving a high hardness and strength, and excellent high-temperature oxidation resistance make HEAs highly promising for application and research and development of these alloys [6-9]. Properties of AlxCoCrFeNi (0 ≤ x ≤ 1) HEAs vary significantly with x [10]. For instance, the alloy structure changes from FCC to BCC for increased Al content x. Besides, the coefficient of thermal expansion decreases with x. Both properties are closely related to the bond strength of alloys. Moreover, electrical resistivity of AlxCoCrFeNi alloys is large, i.e.,

**multi-principal alloys – The high-entropy alloys (HEAs)**

unit cell that SKC called it a pseudo-unitary lattice in 2010 [4].

approximately up to 200 cm [11].

**1. Introduction**


**1. Introduction**

The most extensively used building material around the globe is concrete [1]. Normal concrete is made by mixing coarse aggregate, fine aggregate, cement, water, and admixture in a mixer according to ASTM C192-02. In TSC, coarse aggregates are set in formwork, and then grout or mortar is infused through a pipe with high pressure from the bottom to the top. The grout fills the pores between the coarse aggregates [2]. Maximum density is achieved without mechanical compaction or using a vibrator [3]. In contrast to conventional concrete, compressive stresses in TSC are first passed through the body of coarse aggregates due to point-to-point contact and, after deformation, they then pass through the hardened mortar [2]. TSC is environmentally friendly concrete as the coarse aggregates are not mixed in a mixer, which reduces the consumption of energy. The grout is made on-site, which eliminates the usage of transit trucks, which in turn results in decreasing pollution and reduces cost [4]. The cost of TSC is 40% less than that of traditional concrete because it consists of about 70% coarse aggregate, consuming about 30% less cement [5]. Due to

**Citation:** Javed, M.F.; Durrani, A.A.; Kashif Ur Rehman, S.; Aslam, F.; Alabduljabbar, H.; Mosavi, A. Effect of Recycled Coarse Aggregate and Bagasse Ash on Two-Stage Concrete. *Crystals* **2021**, *11*, 556. https:// doi.org/10.3390/cryst11050556

Academic Editor: Yifeng Ling

Received: 16 April 2021 Accepted: 13 May 2021 Published: 16 May 2021

**Publisher's Note:** MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.

**Copyright:** © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

point-to-point contact of the coarse aggregates, the modulus of elasticity of TSC is very high [6]. Drying shrinkage in TSC is lower than in normal concrete, which results in less volume change [7]. TSC is mainly used where a low heat of hydration is required, such as mass concreting in tunnels, and underwater construction and repair [6].

Around 25 billion tons of concrete is produced annually, making it the largest consumer of Earth's natural resources, which are water, natural aggregates (gravel and crushed rock), and sand [8]. Around 12.6 billion tons of natural aggregate is used annually [9]. Due to urbanization, a lot of construction and demolition waste (CDW) is produced. CDW has a serious impact on our environment as it creates pollution when it is disposed of in landfills. Over 1 billion tons of CDW is produced annually [9]. To protect our environment from depleting virgin aggregate resources, recycled coarse aggregates (RCA) have been used to produce concrete [10]. RCA consists of natural aggregates and adhered mortar. Concrete obtained from demolished buildings is crushed to obtain RCA. Due to increased absorption capacity, 5% more water is required for concrete made with RCA to acquire a similar workability as that of normal concrete [11]. Due to traverse cracks in RCA, increased porosity, less information regarding the interfacial transition zone (ITZ) between RCA and cement paste, impurities, adhered mortar, and inferior quality, this makes the use of RCA as structural concrete difficult [12]. RCA has two ITZs, one with new cement paste and the other with old mortar. Therefore, the structure of concrete made with RCA demonstrates a more complex structure than that of concrete made with natural aggregates. Old ITZ has micro-cracks that decrease the strength of the concrete and also increase its water consumption [13]. RCA may contain impurities such as organic matter, sulphates, carbonates, and chlorides [14]. When Sheen et al. [15] made concrete using RCA, it was observed that the compressive strength of the concrete with RCA decreased because of fine particles. The compressive strength of the concrete with RCA can be increased by adding natural admixtures [16]. The permeability of the concrete can be increased by increasing the amount of the RCA [17]. The shape and texture of RCA depends on the crusher plant, which directly affects the workability of the concrete [18]. Pakistan is an agricultural country. Sugar cane is the second largest cash crop of Pakistan, which accounts for 3.6% of gross domestic product [19]. Bagasse is a by-product of the sugar industry and is used as an energy source for sugar production in this industry [20]. Sugarcane contains about 25% bagasse. Fourteen million tons of bagasse is produced in Pakistan annually. Bagasse is also used in the paper industry. When bagasse is burnt for energy purposes, it produces 3% ash, which is dumped in landfills [21]. Waste obtained from agriculture and some other industries can be used as a partial replacement of cement in concrete [22]. One of the ways to decrease the negative environmental impact of concrete is to use mineral admixtures as a partial replacement of cement, which will not only reduce pollution but will also decrease the cost and improve the strength of the concrete [23].

The objective of this research is to evaluate the mechanical properties of TSC made with NCA and RCA. In order to achieve the objective, four mixes of TSC were prepared. One mix was prepared with 100% NCA, while in the other three mixes, NCA was replaced with 100% RCA. Bagasse ash was used as a partial replacement of the cement at 10% and 20% in two mixes of the TSC that had RCA. Compressive strength, compressive strength at 250 ◦C, tensile strength, and mass loss at 250 ◦C were then determined. In addition, two mixes of conventional concrete were also prepared. One mix was prepared with 100% NCA, while the other mix was prepared with 100% RCA. The results of the compressive strength of the conventional concrete were then compared to that of the TSC.

### **2. Materials and Methods**

### *2.1. Materials*


**3.4 Epicardial ablation and high-power short-duration ablations**

Two new techniques used for the catheter ablation of cardiac arrhythmias are epicardial ablation and high-power short-duration ablation. The approach in epicardial ablations is similar to that in endocardial ablations, including activation mapping, entrainment mapping, pace mapping, and substrate mapping. However, the optimal access technique and the better prevention of complications remain a subject of future research.

Electrophysiologists should be well-versed in the indications and contraindications of the epicardial approach, as well as different puncture techniques and periprocedural complications. From the posterior approach, anterior approach, needle-in-needle approach, fluoroscopic method, and wire-guided puncture technique, interventionists can select the most appropriate strategy. The surgical method should be considered in the event of pericardial adhesions. Contrastenhanced computed tomography may have additional benefits, primarily in terms of detecting abnormal anatomical, dynamic, and perfusion characteristics, but also in terms of distinguishing between epicardial fat and scar tissue.

High-power short-duration RFA is defined in a variety of ways, with power ranging from 40 to 90 W and lasting less than 15 seconds per lesion. PV isolation has been a standard strategy for the catheter ablation of AF since the pioneering work of Hassaguerre et al. in 1994 [27]. However, the long procedure times and high rates of PV reconnection that result have sparked interest in using high-power short-duration ablation. To determine the efficacy and safety profile of this novel technique, researchers looked at the particular biophysical ablation characteristics of HPSD ablation.

#### **3.5 Conclusions on radiofrequency ablation**

In conclusion, while RFA has demonstrated significant benefits in the treatment of arrhythmias, some issues remain debatable and long-term results are still needed.

### **4. Summary**

Heart rate management and control continues to be a serious problem in medicine, requiring a variety of measures, including the development of implantable cardiac devices and, in particular, the methods and medical indications for their use in the interests of an ever-widening cohort of patients in their various life and health conditions.

Such situations as pacing after syncope, pacing following transcatheter aortic valve implantation, and cardiac resynchronization therapy for both heart failure and the prevention of pacing-induced cardiomyopathy have been of ongoing interest. Automatic pacing rate control responding to the metabolic demand of the organism and pacing in various diseases of the heart, including new diagnostic tools for semiautomatic decision-making on pacing, as well as pacing the His bundle and the left bundle branch, are of intensive recent research.

New techniques are introduced for the catheter ablation of cardiac arrhythmias: epicardial ablation and high-power short-duration radiofrequency ablation. Although both the methods have demonstrated significant benefits in the treatment of arrhythmias, some issues remain debatable and long-term results are still needed. The same goes for the application of both the methods of ablation and pacing, together, although it has been used in medical practice. The combined application of both the methods of ablation and pacing has been used in medical practice, and the effectiveness of the results requires continued research. The optimal access technique and the better prevention of complications remain a subject of future research [28–32].

Finally, the experienced authors of the chapters in the present book will certainly make a significant contribution to the progress of cardiac rhythm management. Moreover, IntechOpen has made substantial contributions to the publishing of scientific and practical results in the field, and a number of books have been issued during the last decade [33–36].

*Introductory Chapter: Modern Methods and Devices for Cardiac Rhythm Management DOI: http://dx.doi.org/10.5772/intechopen.104947*


**1. Introduction**

Vocalized emotional expressions such as laughter and surprise (usually accompanied by verbal interjectional utterances) often occur in daily dialogue interactions, having important social functions in human-human communication. Laughter and surprise utterances are not only simply related to funny or emotional reactions but also can express an attitude (like friendliness or interest) [1, 2].

Therefore, it is important to account for such vocalized emotional/attitudinal expressions in robot-mediated communication as well. Since android robots have a highly humanlike appearance, natural communication with humans can be achieved through several types of nonverbal information, such as facial expressions and head/body gestures. There are numerous studies regarding facial expression generation in robots [3–11]. Most of these are related to symbolic (static) facial expression of the six traditional emotions (happy, sad, anger, disgust, fear, and surprise). However, in real daily interactions, humans can express several types of emotions and attitudes by making subtle changes in facial expression and head/ body motion.

When expressing an emotion, humans not only use facial expressions but also synchronize other modalities, such as head and body movements as well as vocalic expressions. Due to a high humanlike appearance in androids, the lack of a modality or of a suitable synchronization among different modalities can cause a strongly negative impression (the "uncanny valley"), when an unnatural facial expression or motion is produced. Therefore, it is important to clarify methodologies to generate motions that look natural, through appropriate timing control.

The author's research group has been working on improving human-robot communication, by implementing humanlike motions in several types of humanoid robots. So far, several methods for automatically generating lip and head motions of a humanoid robot in synchrony with the speech signal have been proposed and evaluated [12–15]. Throughout the evaluation experiments, it has been observed that more natural (humanlike) behaviors by a robot are expected, as the appearance of the robot approaches the one of a human, such as in android robots. Furthermore, it has been observed that unnaturalness occurs when there is a mismatch between voice and motion, especially during short-term emotional expressions, like in laughter and surprise. To achieve a smooth human-robot interaction, it is essential that natural (humanlike) behaviors are expressed by the robot.

In this chapter, motion generation for two vocalized emotional expressions, laughter and surprise, is being focused on. These are usually shorter in duration in comparison to other emotion expressions like happiness, sadness, anger, and fear, and thus it is important to account for a suitable timing control between voice and movements of facial parts, head, and body. The control of different modalities is investigated for achieving natural motion generation during laughter and surprise events of humanoid robots (i.e., when the robot produces a laughter or a vocalized surprise reaction).

In Section 2, related works on motion analysis and generation during emotion expression are presented. In Section 3, the motion generation methods for laughter and surprise expressions are described, along with the motion control methods of an android robot. The motion generation methods are based on analysis results of human behaviors during dialogue interactions [16, 17]. Sections 4 and 5 present evaluation results on the effectiveness of controlling different modalities of the face, head, and upper body (eyebrow raising, eyelid widening/narrowing, lip corner/cheek raising, eye blinking, head motion and torso motion control) and different motion control levels for laughter and surprise expressions. The effects of each modality are investigated through subjective experiments using an android robot as test bed. Section 6 concludes the chapter and presents future work topics. The contents of this chapter are partially included in the author's previously published studies [18, 19]. Readers are invited to refer to those studies, for more details on the motion analysis results.


The American Landscape Architecture Research Universe and a Higher Education Ordination: Descriptive Insights into the Discipline and Profession of Landscape Architecture

*Chunqing Liu, Xiaowen Jin, Zhi Yue, Zhen Wu and Jon Bryan Burley*


*2.1. Chemicals*

All chemicals and reagents used in this study, e.g., trichloroacetic acid (TCA), sodium dodecyl sulfate (SDS), potassium hydroxide (KOH), and potassium chloride (KCl), were acquired from Sigma-Aldrich (St. Louis, MO, USA).

### *2.2. Collection and Preparation of Pig Brains*

Ten brains of crossbred pigs (Landrace–Large white–Duroc, LLD) at 4 months of age were collected from the Shaw Processing Food Co., Ltd. in Nakhon Si Thammarat, Thailand. The brains came from healthy pigs, approved by Thailand's Bureau of Livestock Standards and Certification. Within 1 h, the obtained samples were delivered to Walailak University's Food Technology and Innovation Laboratory in ice with a sample-to-ice ratio of 1:2 (*w/w*). The brains were then rinsed in cold water (4 ◦C), drained, and chopped with a Talsa Bowl Cutter K15e (The Food Machinery Co., Ltd., Kent, UK) to create a homogeneous composite sample. After vacuum packing (DZQ-400, Afapa Vacuum Equipment Co., Ltd., Shanghai, China), ground samples were kept at −80 ◦C for no more than 1 month before being utilized experimentally.


**3. Fundamentals of microbiology and biochemistry in anaerobic digestion**

One of the key factors in the success of microbial-mediated processes is an adequate understanding of process microbial, more specifically the study of microscopic organisms involved in wastewater degradation and byproduct formation. The low growth rate, the specific nutrient and trace mineral requirements of methanogens, coupled with their susceptibility to changes in environmental conditions demand meticulous process control for stable operation (Khanal, 2008). The biochemistry mainly involves enzyme-mediated chemical changes (the chemical activities of microorganism), type of substrate (kind wastewater) microorganism can destroy or transform to new compounds, and the step-bystep pathway of degradation (Sachdeva et al., 2000).


*Edited by M. Mahruf C. Shohel*

E-learning and digital education approaches are evolving and changing the landscape of teaching and learning at all levels of education throughout the world. Innovation of emerging learning technologies is assisting e-learning and digital education to meet the needs of the 21st century. Due to the digital transformation of everyday practice, the process of learning and education has become more self-paced and accessible at any time from anywhere. The new generations of digital natives are growing up with a set of skills through their engagement with the digital world. In this context, this book includes a collection of chapters to facilitate continuous improvements including flexibility and accessibility in e-learning and digital education by exploring the challenges and opportunities of innovative approaches through the lenses of current theories, policies, and practices.

ISBN 978-1-83962-589-3

E-Learning and Digital Education in the Twenty-First Century

Published in London, UK © 2022 IntechOpen © Chonlachai / iStock


**5. Conclusions**

In this work, a prosthesis made of PVDF was manufactured satisfactorily with a 3D printer. It was also tested as pressure and temperature sensors. The characterization could be achieved satisfactorily. As shown in **Figures 7** and **8**, the typical response of the PVDF pressure and temperature sensors was found to be very reliable. It was seen that PVDF displayed a high sensitivity to pressure changes in the range 0–16.35 kPa.

Smart PVDF prostheses provide a promising tool for measuring pressure and temperature variations due to its ferroelectric properties (piezoelectricity and pyroelectricity) [5, 36]. These kind of smart prostheses have great potentialities in the biomedical engineering field because of their ability to generate an electrical potential in response to applied mechanical stress or variations of temperature, as well as flexibility [37].

Besides this, the prosthesis has displayed to be not only a reliable temperature and pressure sensor but also an acoustic one [31, 38]. This is a quite important characteristic due to the fact that the outer ear collects sound waves and channels them into the ear canal where the sound is amplified.

The light response was also satisfactory of the PVDF coinciding with the photopyroelectric techniques reported [11–13].

Finally, it is possible to manufacture sensors for TSPL based on PVDF with their respective feedback, that is, TSPL responses proportionate electrical stimulation of skin sensory nerves.


**4.3. Congeners of HAART**

The currently available anti-retroviral drugs specifically inhibit a select few steps of HIV replication such as HIV entry and fusion, reverse transcription, protease action and integration. Apart from their beneficiary action, the anti-retroviral drugs possess significant adverse reactions which form the principal reason behind poor compliance and drug withdrawal. With the advent of pharamacological techniques, congeners of anti-retroviral drugs are being developed with the aim of minimizing the side effects.

The congeners are molecules of any particular drug class which are engineered to overcome the pitfalls faced by the existing members of the same drug class. They possess minor structural modifications that confer one or more favourable properties such as increased biovailability, increased target site binding affinity or longer half life. By virtue of these properties, the congeners can be effectively administered at reduced dose and interval and hence possess a low adverse effect profile. The congeners are subject to clinical trials and would probably fail or get pass the trial stages to get approved by the United Staes Food and Drug Administration (FDA) and relevant international bodies. Table-1 summarizes the FDA approved antiretroviral dugs for use in the USA and their congeners in the pipeline (updated to October 2014) [18-21].

**Table 1.** Anti-retroviral drugs approved by the FDA and their congeners under consideration

#### **4.4. Reducing the pill burden**

**4.3. Congeners of HAART**

2014) [18-21].

**inhibited**

receptor

membrane

**Stage of HIV replication**

Attachment to CCR5 co-

Fusion of envelope with cell

Reverse transcription Nucleoside / Nucleotide

Reverse Transcriptase Inhibitors (NRTIs)

Non-Nucleoside Reverse Transcriptase Inhibitors

(NNRTIs)

developed with the aim of minimizing the side effects.

214 Trends in Basic and Therapeutic Options in HIV Infection - Towards a Functional Cure

The currently available anti-retroviral drugs specifically inhibit a select few steps of HIV replication such as HIV entry and fusion, reverse transcription, protease action and integration. Apart from their beneficiary action, the anti-retroviral drugs possess significant adverse reactions which form the principal reason behind poor compliance and drug withdrawal. With the advent of pharamacological techniques, congeners of anti-retroviral drugs are being

The congeners are molecules of any particular drug class which are engineered to overcome the pitfalls faced by the existing members of the same drug class. They possess minor structural modifications that confer one or more favourable properties such as increased biovailability, increased target site binding affinity or longer half life. By virtue of these properties, the congeners can be effectively administered at reduced dose and interval and hence possess a low adverse effect profile. The congeners are subject to clinical trials and would probably fail or get pass the trial stages to get approved by the United Staes Food and Drug Administration (FDA) and relevant international bodies. Table-1 summarizes the FDA approved antiretroviral dugs for use in the USA and their congeners in the pipeline (updated to October

**Anti-retroviral drug class FDA approved agents Congeners**

Entry inhibitors Maraviroc Cenicriviroc

Fusion inhibitors Enfuvirtide Albuvirtide

Zidovudine Lamivudine Stavudine Didanosine Emtricitabine Abacavir

Tenofovir disoproxil

fumarate

Nevirapine Efavirenz Delaviridine Etravirine Rilpivirine

Vicriviroc Adaptavir INCB-9471 PRO-140

tenofovir Amdoxovir Racivir Festinavir Elvucitabine Dexelvucitabine

Doravirine

Tenofovir alafenamide Hexadecycloxy propyl One of the practical difficulties faced by the multi-drug HAART regimen is the pill burden. It is glaringly obvious and even scientifically proven that, therapeutic regimens with lesser number of pills have a better patient adherence [22]. In this context, pills with a fixed dose combination of more than one anti-retroviral agent are being developed and few have also been approved by the FDA. Table-2 summarizes the list of combinations approved by the FDA as of October 2014 [18].

**Table 2.** Fixed dose combinations of anti-retroviral drugs approved by the FDA

Designing a single drug molecule containing the active moieties of two different anti-retroviral compounds is yet another strategy to reduce the pill burden. These molecules termed 'port‐ manteau inhibitors' can exert their anti-retroviral action at two different steps of HIV replica‐ tion and could thereby reduce an extra pill. Caffeoyl-anilide compounds are evaluated for their dual action in inhibiting HIV integrase and blocking the CCR5 receptor mediated entry [23].