**2. Critical environmental conditions for bio-deterioration**

There are several biological processes causing aging and damage to buildings and building components. This is due to natural ageing of materials but also caused by excessive moisture and damage of materials. For mould development, the minimum (critical) ambient humidity requirement is shown to be between RH 80 and 95 % depending on other factors like ambient temperature, exposure time, and the type and surface conditions of building materials (Table 1) For decay development, the critical humidity is above RH 95 %. Mould typically affects the quality of the surfaces and the adjacent air space with volatile compounds and spores. The next stage of moisture induced damage, the decay development, forms a serious risk for structural strength depending on moisture content, materials, temperature and time. The worst decay damage cases in North Europe are found in the floors and lower parts of walls, where water accumulates due to different reasons.

Moisture and Bio-Deterioration Risk of Building Materials and Structures 581

activity on germination and growth of selected mould fungi. They developed isopleths for the growth conditions of mould fungi on agar media. An isopleths is a boundary that defines all combinations of temperature and relative humidity that permit a particular mould growth rate. Grant et al. (1989) analysed and modelled the moisture requirements of some mould fungi isolated from dwellings. A certain succession, depending on the moisture requirements of different fungal species: primary, secondary and tertiary colonizers, was

Research with building materials will be better fitted to the moisture problems in buildings. Adan (1994) used a non-linear regression technique to model sigmoid curves describing vegetative fungal growth of *Penicillium chrysogenum* on gypsum board material. He used the time-of-wetness (TOW) as an overall measure of water availability for fungal growth under fluctuating humidity conditions. The TOW is defined by the ratio of the cyclic wet period (RH ≥ 80 %) and the cyclic dry period. The mould growth is a function of the effect of lowest humidity, time of wetness and high relative humidity frequency, and finally of periods of wet and dry conditions. He used Low Temperature Scanning Electronic Microscope LTSEM to analyse the growth and studied the effect of coatings and surface quality on the mould growth. He also evaluated the effect of distribution of growth density on test results. Clarke et al. (1998) developed a simulation model and tool for mould growth prediction in buildings based on an analysis of published data using growth limit curves for six generic mould categories. These limits have been incorporated within the ESP-r (building Energy Software) system for use in conjunction within combined heat and moisture flow

Modelling of mould growth and decay development based on humidity, temperature, exposure time and material will give tools for the evaluation of durability of different building materials and structures. The models make it possible to evaluate the risk and development of mould growth and to analyse the critical conditions needed for the start of growth of microbes and fungi. The model is also a tool to simulate the progress of mould and decay development under different conditions on the structure surfaces. This requires that the moisture capacity and moisture transport properties in the material and at the surface layer have been taken into account in the simulations. In practice there are even more parameters affecting mould growth, e.g. thickness of the material layers combined with the local surface heat and mass transfer coefficients. Therefore, the outcome of the simulations and in-situ observations of biological deterioration may not agree. One of the results of a newly finished large Finnish research project "Modelling of mould growth" is an improved and extended mathematical model for mould growth based on development of

mould index in different materials under different exposure conditions (table 2).

the large laboratory studies on Scots pine and Norway spruce sapwood.

Hukka and Viitanen (1999) and Viitanen et al. (2000) presented a model of mould growth which is based on duration of suitable exposure conditions required before microbial growth will start or the damage will reach a certain degree. Particular emphasis is focused on this time period, the so-called response time or response duration, in different humidity and temperature conditions for the start of mould growth (Figure 1). The model is based on

found.

simulation.

**3. Modeling of development of mould growth**

**3.1 Mould growth on building materials**

Table 1. Organisms involving damages and defects of building components (Viitanen and Salonvaara 2001, Viitanen et al. 2003)

In Northern Europe, the roofs, floors and lower parts of walls are most often exposed to high humidity and potential attack by biodeterioration processes (Paajanen and Viitanen 1989, Viitanen 2001a, Kääriäinen et al. 1998) when also decay will develop. For the decay development, the humidity and moisture conditions will be higher than that for mould growth, and modelling of decay risk is a separate task. Mould growth is often typical in materials in exterior conditions. In damage conditions, however, different decay types can be found: brown rot, soft rot, and white rot. In buildings suffering from excessive moisture loading, brown rot is the most common decay type (Paajanen and Viitanen 1989, Viitanen 2001a).

The other a-biotic factors like UV radiation and quality of substrate (nutrients, pH, hygroscopicity, water permeability) are also significant for the growth of organisms. Different organisms, e.g. bacteria, fungi and insects, can grow and live in the building materials; microbiologically clean buildings probably do not exist, as some contamination begins as early as during the construction phase. The humidity / moisture conditions connected with temperature and exposure time are the most important factor for development of biological problems and damage in buildings.

The research and modelling of mould growth is most often performed under constant conditions when the ambient humidity conditions and microclimate will prevail for longer periods. Ayerst (1969) and Smith and Hill (1982) studied the effect of temperature and water

120 % RH > 95 %

**(RH or MC %)**

wet materials RH > 97 %

Ambient RH > 75 %, depends on duration,

Ambient RH > 95 %,

species and materials

Ambient RH > 65 % depends on duration, temperature, species and

wet materials also nitrogen and low pH are needed

environment

Table 1. Organisms involving damages and defects of building components (Viitanen and

In Northern Europe, the roofs, floors and lower parts of walls are most often exposed to high humidity and potential attack by biodeterioration processes (Paajanen and Viitanen 1989, Viitanen 2001a, Kääriäinen et al. 1998) when also decay will develop. For the decay development, the humidity and moisture conditions will be higher than that for mould growth, and modelling of decay risk is a separate task. Mould growth is often typical in materials in exterior conditions. In damage conditions, however, different decay types can be found: brown rot, soft rot, and white rot. In buildings suffering from excessive moisture loading, brown rot is the most common decay type (Paajanen and Viitanen 1989, Viitanen

The other a-biotic factors like UV radiation and quality of substrate (nutrients, pH, hygroscopicity, water permeability) are also significant for the growth of organisms. Different organisms, e.g. bacteria, fungi and insects, can grow and live in the building materials; microbiologically clean buildings probably do not exist, as some contamination begins as early as during the construction phase. The humidity / moisture conditions connected with temperature and exposure time are the most important factor for

The research and modelling of mould growth is most often performed under constant conditions when the ambient humidity conditions and microclimate will prevail for longer periods. Ayerst (1969) and Smith and Hill (1982) studied the effect of temperature and water

temperature and mould species

Wood moisture content > 25 -

MC > 25 - 120 %, depends on duration, temperature, fungus **Temperature range (**°**C)**

ca. -5 to +60

ca. 0 to +50

ca. -5 to +45

ca. 0 to +45

ca. 0 to +45

ca. 5 to +50

**Damage / problem type Humidity or moisture range**

**Type of organism**

blue-stain fungi

algae and lichen

2001a).

bacteria bio corrosion of many

mould fungi surface growth on

different materials, smell,

wood (soft rot, brown rot or white rot), also many other materials can be

Strength loss of materials.

Surface growth of different materials on outside or weathered material.

development of biological problems and damage in buildings.

health problems

different materials, smell and health problems

blue-stain of wood permeability change of wood

decay fungi different types of decay in

deteriorated,

insects Different type of damage

Salonvaara 2001, Viitanen et al. 2003)

in organic materials, surface failures or strength loss.

activity on germination and growth of selected mould fungi. They developed isopleths for the growth conditions of mould fungi on agar media. An isopleths is a boundary that defines all combinations of temperature and relative humidity that permit a particular mould growth rate. Grant et al. (1989) analysed and modelled the moisture requirements of some mould fungi isolated from dwellings. A certain succession, depending on the moisture requirements of different fungal species: primary, secondary and tertiary colonizers, was found.

Research with building materials will be better fitted to the moisture problems in buildings. Adan (1994) used a non-linear regression technique to model sigmoid curves describing vegetative fungal growth of *Penicillium chrysogenum* on gypsum board material. He used the time-of-wetness (TOW) as an overall measure of water availability for fungal growth under fluctuating humidity conditions. The TOW is defined by the ratio of the cyclic wet period (RH ≥ 80 %) and the cyclic dry period. The mould growth is a function of the effect of lowest humidity, time of wetness and high relative humidity frequency, and finally of periods of wet and dry conditions. He used Low Temperature Scanning Electronic Microscope LTSEM to analyse the growth and studied the effect of coatings and surface quality on the mould growth. He also evaluated the effect of distribution of growth density on test results. Clarke et al. (1998) developed a simulation model and tool for mould growth prediction in buildings based on an analysis of published data using growth limit curves for six generic mould categories. These limits have been incorporated within the ESP-r (building Energy Software) system for use in conjunction within combined heat and moisture flow simulation.


**Acknowledgements**

complexes have high ϕ of 49–90% and τ of 4.1–17.7 μs in CH2

these complexes that showed very high brightness, even up to 66,000 cd/m2

94 Light-Emitting Diode - An Outlook On the Empirical Features and Its Recent Technological Advancements

**7. Other types of tetradentate platinum(II) complexes**

ture above 400°C, and one device exhibited a peak EQE of 22.3% [59].

Ir(mppy)3

**8. Conclusion**

parable to that of the Ir(mppy)3

the planar rigid molecular configuration enabled the fluorine-containing complexes **54**–**56** to have strong excimer emission at 616–624 nm, making them serve as ideal emitters for singledoped white OLEDs with CRI of up to 76 [52]. However, after introducing sterically bulky 3,5-di-*tert*-butylphenyl group to the pyridine ring, excimer formation was suppressed for the complexes **57**–**62**. Devices doped with complex **58** bridging phenylamine or complex **59** with a spiro linkage demonstrated peak EQEs over 25% and maximal PEs up to 109.4 lm/W using TmPyPB as ETL. The maximal PE of complex **59** could further be improved to 126.0 lm/W if Tm3PyBPZ as ETL, which were the highest among the reported platinum(II)-based OLEDs [53]. In the same year, Che's group developed another series of tetradentate platinum(II) complexes containing carbazole (**60**), phenoxazine (**61**), and phenothiazine (**62**) moieties, which served as

yellow phosphorescent emitters combined with blue emitter to make white OLEDs [54].

Besides the four series of tetradentate platinum(II) complexes discussed above, there were also some other new types. In 2015, a series of sky-blue emitters based on 3-(trifluoromethyl)- 5-(2-pyridyl)pyrazole or 3-(trifluoromethyl)-5-(2-pyridyl)-1,2,4-triazole containing spiroarranged tetradentate ligands were developed. The peak EQE of one blue OLED could reach 15.3% and CIE values of (0.190, 0.342) [58]. In 2017, Liao, Fan, and co-workers developed three 1-isopropyl-2-phenyl-benzo[*d*]imidazole-based emitters with decomposition tempera-

Very recently, Fukagawa and co-workers reported great progress in ultrapure green OLEDs based on a NHC emitter PtN7N [60], which was developed by Li′s group before 2014 [61]. The optimized OLED showed CIE coordinates of (0.18, 0.74) using a top-emitting OLED with a microcavity structure and also using a boron-based host material [60]. Fukagawa's work demonstrated that the narrowband emitter PtN7N was superior to the iridium(II)-based emitter

definition displays [60], owing to the very small vibrational structures of PtN7N that could be well suppressed by microcavity technology. Similar phenomenon was also observed in the previous report of narrowband green emitter PtN1N vs. PtOO3 [62]. Moreover, Fukagawa's work also demonstrated that the operational stability of PtN7N-based OLEDs could be com-

In summary, after over 10 years of development, the emission spectra of the tetradentate platinum(II)-based OLEDs can cover the whole visible spectrum, they also exhibit high efficiency, and some show high color purity and long operational lifetime, demonstrating their

tion of PtN7N by employing suitable host and charge-transporting materials [60, 63].

for the development of ultrapure green emitter to satisfy the BT.2020 for ultrahigh-

Cl2

solutions, and the OLEDs doped

at 10.5 eV. Moreover,

The authors thank the National Natural Science Foundation of China (21602198, 21776259, 21476270), the "Qianjiang Talents Plan" (QJD1602017), and AAC Technologies for their financial support. The authors also thank Dr. Tyler Fleetham from the University of Southern California for the measurements of the quantum efficiency and luminescent lifetime of the PtON3.


*Proceedings* **Possibilities of Recovery of Industrial Waste and By-Products in Adobe-Brick-Type Masonry Elements** †

## **Gabriela Călătan, Andreea Hegyi \*, Elvira Grebenisan and Anamaria Cătălina Mircea**

NIRD URBAN-INCERC Cluj-Napoca Branch, 117 Calea Flores,ti, 400524 Cluj-Napoca, Romania<EMAIL_ADDRESS>(G.C<EMAIL_ADDRESS>(E.G<EMAIL_ADDRESS>(A.C.M.)

**\*** Correspondence<EMAIL_ADDRESS>
† Presented at the 14th International Conference INTER-ENG 2020 Interdisciplinarity in Engineering, Mures, , Romania, 8–9 October 2020.

Published: 9 December 2020

**Abstract:** The purpose of this study is to search for possibilities to capitalize on industrial waste, which occupies huge storage spaces. This paper presents an experimental study on the possibility and efficiency of this industrial waste in the composition of clay mixtures suitable for making unburned clay bricks. Living in harmony with nature is part of sustainable development. For this purpose, six compositions based on clay and industrial waste were made. The studied industrial wastes were: ash from the Mintia thermal power plant, Romania, limestone sludge, gypsum sludge, and damped waste from the processing of imported ore.

**Keywords:** adobe bricks; thermal power plant ash; dumped waste; limestone sludge; plaster sludge

### **1. Introduction**

It is known that the cement industry produces air pollution due to CO2 emissions, which constitute 4–8% of total greenhouse gas emissions. Other non-negligible emissions that occur in the cement industry are dust emissions and emissions of N2O, CH4, SOx, NOx, NH3, and CO [1]. All this results in a depletion of the ozone layer and, therefore, global warming. Under these conditions, the elimination or substantial reduction of cement consumption is desirable. By replacing classic building materials with environmentally friendly materials wherever possible, a considerable contribution is made to protecting the environment. The possibilities of recycling, reuse, reintegration in nature, environmental protection, and efficient management of natural resources are essential indicators in the context of sustainable development. Living in harmony with nature is part of sustainable development. Products that successfully meet all these requirements are the elements of unburned clay masonry.

Another important quality of ecological materials is the fact that they offer a healthy and pleasant climate to users. Clay-based building materials used in construction allow a natural and efficient ventilation of the walls, permeability to water vapor, thermal constancy, and a constant humidity of the indoor environment In addition, these walls made of clay-based bricks have no toxic emissions, a factor that plays a very important role in reducing the risk of respiratory diseases, allergies, and more. Studies are presented in the specialized literature that demonstrate the durability of constructions made with local materials and local techniques in different geographical and climatic conditions [2–4].

Nine thousand years ago, construction techniques with clay bricks were used. Clay bricks were discovered in Turkistan, dating from 8000–6000 BC. Clay was used as a building material in all ancient cultures for religious buildings and houses; 5000-year-old foundations were discovered in Assyria [5].

Houses made of ecological materials have started to become more and more known and pleasant in Romania, and more and more specialists are interested in this type of construction [6,7]. The specialized literature presents the results of some research carried out in view of the possibility of realizing such constructions from clay. These results, in addition to the many benefits, also point out some drawbacks due to the clay [1,8–10]. The main drawbacks are that, in order to obtain the minimum conditions of mechanical and thermal resistance, a large wall thickness is required. There is also a high risk of cracking during drying due to significant axial contractions. The ideal clay soil to be used in construction must contain at least 15–16% clay because it has the right plasticity and workability to obtain a quality finished product [9,10]. In order to obtain a workable mixture, a certain amount of water is needed to induce the phenomenon of thinning of the clay sheets, but it must be dosed so as not to reach significant axial contractions and the appearance of cracks during drying. Thus, a linear contraction between 3% and 12% is accepted for bricks from soft mixtures or between 0.4% and 2% in the case of drier mixtures [1,8,9,11].

In order to obtain a good thermal insulation, the specialized literature indicates an apparent density of the material between 1600 and 2000 kg/m3 [1,8,11,12].

The studies presented until now in the literature do not adequately show the influence of various additives on the physical–mechanical characteristics of products made of clay (mechanical strength, thermal resistance, water behavior and water vapor, etc.). Among the additives that could be used for the clay matrix, but which have been insufficiently studied until now, is industrial waste. Every year, after burning coal in order to obtain thermal energy, large quantities of power plant ash are produced. The use of coal in the thermal energy production process in Romania has a share of over 38% of the entire electricity production in the country [13,14].

The ash resulting from the burning of coal can be of two types: fly ash, which is evacuated with the flue gases, and coarse ash, which is collected centrally and transported to specially arranged places in dumps. Both types of ash have a major impact on pollution; flying ash pollutes the air, and coarse ash occupies huge areas of land. In Romania, over 80% of industrial waste is stored in places arranged in nature; this is the main method for so-called ash disposal. A single thermal power plant in Romania produced almost 650,000 tons of ash, 50,000 tons of slag, and 50,000 tons of gypsum in 2017. Of the total industrial waste produced at the national level, only 0.06% is currently recovered [13,15].

In addition, within the technological process of the processing of natural stones and marble (limestone blocks), there are significant quantities of sludge—an average of 20 tons/day [13]. The resulting limestone sludge, which is partially dry, is stored in heaps in the form of cakes, drying naturally.

Another category of industrial waste is gypsum sludge resulting from the processing of imported ore. This plaster slime is stored in heaps, occupying large spaces as well. Therefore, studies and research are needed for the possibility of recovering this waste. One way of recovery of industrial waste can be by using is as an additive in clay mixtures intended for the manufacture of unburned clay bricks. The aim of this study is to establish optimal clay-based mixtures for the manufacture of unburned bricks, using four types of industrial waste as an addition to clay, as follows: power plant ash and limestone sludge on the one hand, and scrap waste from the processing of imported ore and gypsum sludge on the other.

The purpose of these experimental studies is to find sustainable ways to capitalize on industrial waste.

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

The raw materials used to make the experimental mixtures were: clay that was extracted from Valea Draganului, Cluj Napoca, Romania, ash from the Mintia thermal power plant, Romania, limestone sludge from limestone processing, scrap waste from imported ore processing, and gypsum sludge. These wastes were used simultaneously, two by two: ash with limestone sludge and scrap waste with gypsum sludge.The sandy clay used was characterized by particle size distribution (Figure 1) and oxide composition (Table 1) [16,17].

**Figure 1.** Granulometry of sandy clay [16].

**Table 1.** Oxide composition of clay, determined according to romanian standard STAS 9163.

The power plant ash was characterized by the oxide composition presented in Table 2, the particle size distribution of limestone is presented in Table 3, and the apparent density in Table 4 [18].

**Table 2.** The composition of the ash from the Mintia thermal power plant, determined by XRF (X-ray fluorescence) analysis.

The fineness of the ashes from the Minthia thermal power plant, determined on a sieve of 0.045 mm, was 39.20%.

The limestone sludge used had the particle size composition shown in Table 3 and the apparent density shown in Table 4 [18].

**Table 3.** Particle size distribution of limestone sludge.

The apparent densities of all wastes used in this study, determined in the laboratory, are shown in Table 4 [18].

**Table 4.** Apparent density of the filler materials used.

Three compositions of clay, ash, and limestone sludge were made in different proportions, as well as another three compositions of clay, scrap waste, and gypsum sludge in other three proportions. The dumped waste and gypsum sludge came from the same working point for processing the imported ore, and the ash and limestone sludge came from the same area. The compositions of the six mixtures made, as well as that of a control sample (made of clay material without additives), are presented in

Table 5. Prismatic specimens measuring 40 × 40 × 160 mm were made from each mixture and kept until the equilibrium humidity was reached. The parameters that were examined on these specimens, after a visual control of possible cracks appearing in the specimens that reached the equilibrium humidity, were:

The equilibrium humidity is considered to be reached when the constant mass is reached. From previous experiences, it has been found that it occurs about 40 days after making clay-based specimens.

**Table 5.** Compositions of experimentally tested mixtures.

These compositions were tested at 40 days and at one year in order to appreciate the variation of the parameters over time. Samples 1 to 7 were tested at 40 days, and samples 8 to 13 were tested at one year.

## **3. Results and Discussion**

Analyzing the appearance of the specimens at 40 days and at one year, the lack of surface cracks can be noticed, which is a very important aspect for clay-based mixtures, but it must be taken into account that the dimensions of the specimens are small (Figure 2).

**Figure 2.** Appearance of the surface of the hardened specimen.

The results of the axial contractions recorded are represented in Figure 3.

**Figure 3.** Axial contractions of dry mixtures at equilibrium humidity.

It was found that, from the point of view of the axial contractions, all the tested mixtures fell within the limits indicated as being admissible in the specialized literature [1,7,13,18]. Although the results obtained for drying shrinkage and crack evolution were satisfactory on these specimens, it can be stated that for the manufacturing of bricks from these compositions, the dimensions of the elements made must not exceed certain dimensions to avoid cracks. In order to be able to establish a correlation between the maximum permissible dimensions of the elements made from these types of clay mixtures with additions of industrial waste and the absence of cracks, a further study is needed.

Based on the results shown in the graph in Figure 3, it is observed that the additives used in the mixture had a small influence on the axial contractions compared to the control specimen made only of clay. The specimens were checked 40 days (mixtures 1 to 7) and one year (samples 8 to 13) after manufacturing, as shown in Table 5. It was observed that the waste obtained from the processing of the imported ore, as well as the dumped waste and the gypsum sludge added into the clay matrix, induced a more accentuated decrease of the axial contractions compared to when the Mintia ash and the limestone sludge were added in the same proportions.

The most accentuated decrease of the axial contractions was presented by the mixture with 50% clay, 25% dumped waste, and 25% gypsum sludge (sample no. 7), which was from 9.4 mm/100 mm of the control specimen up to 8.6 mm/100 mm. Axial contractions after one year remained constant. There was no significant decrease or increase in axial contractions from 40 days to one year after manufacturing.

The values of the apparent densities are presented in Figure 4.

According to the specialized literature, the materials whose apparent density is between 1600 and 1690 kg/m3, as shown in the graph, have the ability to store heat, which then yields when the temperature drops [1,7,12,13,18]. According to the graph, all compositions fall within this limit. Materials with densities between these values have a good thermal index, which causes a room to have constant temperature. This is an important quality of natural materials.

The mixtures with the lowest values of apparent density at 40 days, 1650 kg/m3, were samples 2 and 5. Sample 2 contained 60% clay and 40% waste (20% ash and 20% limestone sludge), and sample 5 contained 70% clay and 30% waste (15% waste and 15% gypsum sludge).

The sample with the highest apparent density was sample 4, which contained the maximum percentage of added waste (40% clay and 60% other additives). This composition probably had the highest density due to the addition of limestone sludge, which has the highest bulk density compared to other raw materials.

**Figure 4.** Apparent density of mixtures.

After one year, the sample with the highest apparent density was sample 10 which contained 40% clay and 60% waste (30% ash and 30% limestone sludge). In all mixtures, after one year, a small increase of the values of bulk density could be observed, probably due to the reaction between Ca and CO2 from the air that formed the limestone.

The mechanical resistances determined on hardened prisms at the equilibrium humidity after one year are presented in Figure 5. In Figure 6, the appearance of the specimen after breaking can be observed.

**Figure 5.** Mechanical resistance of samples.

A first observation is that all mixtures with added waste have increased mechanical strength compared to the control sample, which was made only with clay. Another important observation is that mechanical strength increases over time. All values of one-year resistance are higher than 40-day resistance.

In the case of the addition of ash and limestone sludge, samples 3 and 9 (25% ash, 25% limestone sludge, and 50% clay) had the highest mechanical strength at 40 days and one year, with 8.2 N/mm2 (sample 3) and 8.9 N/mm2 (sample 9), respectively. With a greater or lesser addition of this type of waste, the strengths are lower compared to that of this mixture. There is an increase in mechanical strength by 47% compared to the control sample at 40 days and by 8% at one year, compared to the same mixture tried at 40 days. For sample 2 (addition of 20% ash and 20% limestone sludge) as well as at sample 4 (30% ash and 30% limestone sludge), there was a small decrease in resistance compared to sample 3, but nevertheless, the mechanical strengths were higher than the strength of the clay without addition.

**Figure 6.** Appearance of test specimens after breaking.

In the case of the addition of dumped waste and gypsum sludge, the sample with the best mechanical resistance at 40 days was sample 6 with 20% dumped waste, 20% gypsum sludge, and 60% clay. The value of the mechanical strength of sample 6 was with 40% higher than that of the control sample. The same mixture tested at one year (sample 12) had a value of compressive strength 10% higher than at 40 days. A higher proportion of piled waste and gypsum sludge reduced the mechanical strength compared to sample 6 when tested 40 days after manufacture. The same mixture tested at one year, sample 12, also had the highest mechanical strength among mixtures with this type of waste. The samples with the addition of 30% and 50% mixtures of dumped waste and gypsum sludge had mechanical strengths of approximately 6% lower than that of sample 6.

The best mixtures analyzed from the point of view of mechanical strength were the mixtures marked with 3 or 9 (50% clay, 25% Mintia ash, and 25% limestone sludge) and samples 6 or 12 (20% dumped waste, 20% plaster sludge, and 60% clay).

#### **4. Conclusions**

After this study, the following conclusions can be drawn.

All mixtures have a good workability, which allows a necessary homogenization.

Axial shrinkage is not negatively influenced by the addition of industrial waste, and no mixtures showed cracks when drying. The largest length of a side of the specimens made was 160 mm, so it can be stated that when making bricks with a side of 160 mm, no cracks appear, but for a brick with a larger side, there is a probability of cracks; therefore, an additional study to establish the maximum possible dimensions without cracks is necessary. Due to the results obtained at 40 days and at one year, it can be stated that the axial contractions remain constant over time.

All the values obtained for the densities in the hardened state were within the interval of 1600–2000 kg/m3. According to the literature, this range is satisfactory in terms of thermal efficiency, so the addition of industrial waste does not negatively influence the values of apparent densities in the hardened state. The apparent density increases very slightly over time.

The mechanical strengths were positively influenced by the addition of waste. The composition with the addition of 25% ash and 25% limestone sludge had the highest mechanical strength of all mixtures. The mechanical strength of this mixture increased by 8% after one year.

The mechanical strength of the sample with the addition of 20% bulk waste and 20% gypsum sludge was also higher than the mechanical strength of the control sample. This mixture had the highest resistance in the case of dumped waste and gypsum sludge.

The resistance value of this sample was 12% lower compared to the sample with 25% ash and 25% limestone sludge. In the test with the addition of 20% dumped waste and 20% plaster sludge, the value of the resistance after one year increased by 10%.

All the conclusions confirm the fact that, in terms of physical–mechanical characteristics, industrial waste can be successfully used as an addition in clay matrixes intended for the production of unburned clay bricks, and it is very welcome to capitalize on industrial waste in this way, resulting in ecological and healthy materials at the same time.

The bricks made according to the studied recipes can be successfully used to make constructions that are environmentally friendly and energy efficient, and that provide a pleasant and healthy climate for the inhabitants; at the same time, nature is protected from pollution by reducing cement consumption. This also preserves the basic principles of traditional vernacular architecture that is modeled according to current technological progress.

**Author Contributions:** Conceptualization, G.C., A.H., E.G., and A.C.M.; methodology, G.C. and A.H.; validation, G.C., and A.H.; formal analysis, A.H. and A.C.M.; investigation, G.C.; data curation, G.C.; writing—original draft preparation, G.C.; writing—review and editing, G.C., A.H., E.G., and A.C.M.; visualization, A.H. and A.C.M.; supervision, A.H. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Conflicts of Interest:** The authors declare no conflict of interest.

#### **References**

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Preface

Inquiring on the sky (i.e., the Universe) has been present as affair of concern of the human kind since the early days of the first hominids like *homo floresiensis* and late *homo sapiens*. Fascination of sky watchers on a starry night, with its planets and the Moon, still today invites the best human minds to struggle for unveiling its secrets. To extending farther out the reach of our eyes, the telescope was introduced to astronomy in 1609 by Galileo Galilei. Since then, technological advances in many branches of physics and astronomy have driven the mankind to more and more astonishing discoveries in the Universe. Such findings were stimulated by a vigorous research enterprise in many areas of the modern technological era, which extends from development of technologies for building spacecrafts, spaceships and for space travel (including space medicine), to modern methods for scrutinizing the Universe in all the spectrum of electromagnetic radiation, and beyond via gravitational wave observatories. Thus, the all-encompassing term *Space Science* was coined to describe all of the various fields of research in science (originally, such fields were considered part of astronomy) that are concerned with the study of the Universe, and generally means either *excluding the Earth* or *outside of the Earth's atmosphere*. This special volume on *Space* Science was prepared upon a scientifically rigorous selection process of each of the contributed chapters making up of it. Its structure drives the reader into a fascinating journey starting from the surface of our planet to reach a boundary where something lurks at the edge of the observable, light-emitting Universe, presenting four Sections running over a timely review on the most recent developments in space exploration and the role being played by newcomer nations, an overview on the early evolution of our planet during its long ancient ice age, a reanalysis of some aspects of satellites and planetary dynamics, to end up with intriguing discussions on recent advances in physics of cosmic microwave background radiation and cosmology.

Section I presents an update on the state-of-the-art on *space exploration*. This term stands for all activities leading to study the Earth outer space by using either space technology or observations from the surface or from our close circumplanetary environment. With the advances in space technology our knowledge on the outer space has been increasing with an accelerating pace. The mankind succeeded to send satellites, landers, rovers and even manned spacecrafts to the Moon. The chapter recalls that the activities of nations involved in the exploration and use of the outer space is governed by the *Outer Space Treaty,* which defines basic principles for using the outer space. Despite the *Treaty* states that "The exploration and use of outer space shall be carried out for the benefit and in the interests of all States", until recent years space exploration was a privilege of a few countries (United States, Japan, Europe and Russian Federation), which managed to develop the technologies necessary to adventure far out of our planet. This chapter discusses extensively a very innovative and recently introduced concept in this field: *the democratization of the space*. Countries wanting to use the space for the good of their citizens and to boost their development stepped into the space technology arena. In the late years China and India made great achievements. As of today, these countries managed to put their own launch vehicles on serial production and even reached lunar orbit. Meanwhile, late industrialized nations like Brazil, South Africa, Turkey, Thailand, Malaysia and some other countries had their first steps mostly through relatively low-cost small satellite technology transfer programs based on technological partnerships with the countries strong in technology for navigation through the solar system. The chapter ends up by listing the set of technological requirements that countries newcomers into outer space research needs to accomplish, and stresses the large investments (man-power and financial) that are expected in order to succeed in such adventure out there.

Preface XI

communication cables are a special category regarding GIC since their lengths imply that the end-to-end voltages associated with GIC are very large. Many other technological structures lying on the Earth surface can be affected by GIC. Understanding this phenomenon, and envisioning solutions and prevention techniques is essential for the progress continued of our modern society, which depends so much on electric power supply. This chapter addresses in an extremely clear manner all the issues related to GIC. Meanwhile, the other chapter in this Section argues that if protoplanets formed from 10 to 20 kilometers in diameter planetesimals, in a runaway accretion process prior to the oligarchic growth into the terrestrial planets, then is logical to ask where these planetesimals may have formed in order to assess the initial composition of the Earth. By following a well-stablished scenario for describing such process the authors compute the efficiency factor for the formation of planetesimals from the pre-solar system nebula, to then using such factor to compute, as a function of the nebula mass, the feeding zones that contributed to material contained within 10, 15 and 20 kilometers in diameter planetesimals at a distance of about 1. A.U. from the Sun. Upon selecting reasonable nebula masses, the planetesimals contain a minimum of 3% water as ice by mass. The fraction of ice increases as the planetesimals enlarge in size and as the nebula mass decreases, since both factors increase the feeding zones from which solids in the planetesimals are drawn. In virtue of this estimate, a couple of questions are raised: Is there really a problem with the current scenario which makes the Earth too dry? Or, is it possible that the nascent Earth lost significant quantities of water in the final stages of accretion till reaching its late (to the present) configuration. The answer found by the authors to those queries appears to suggest that such a

In Section III three articles are offered. One invokes the phenomenon of gravitational slingshot of planets to support an argument in favor of a new mechanism for featuring the evolution of the solar system. Planet fly-by, gravity assist is routinely used to boost the mission spacecrafts to explore the far reaches of our solar system. Voyager I and II used the boost provided by Jupiter to reach Uranus and Neptune. Cassini utilized 4 such assists to reach Saturn. A spacecraft which passes *behind* the moon gets an increase in its velocity (and orbital energy) relative to the primary body. In effect, the primary body launches the spacecraft on an outward spiral path. If the spacecraft flies *infront* of a moon, the speed and the orbital energy decreases. Traveling *above* and *below* a moon alters the direction modifying only the orientation (and angular momentum magnitude). Intermediate fly-by orientation change both energy and angular momentum. Accompanying these actions there are reciprocal reactions in the corresponding moon. The above slingshot effect takes place in a three body problem. In a three body configuration, the heaviest body is the primary body. With respect to the primary body the secondary system of two bodies is analyzed. In case of planet fly-by, the planet is the primary body and the moonspacecraft constitute the secondary system. While analyzing planetary satellites, the Sun is the primary body and the planet-satellite is the secondary system, although in

transition indeed took place.

Section II focuses on the evolution of our planet. It offers a couple of articles. One discusses the effects on the ground due to geomagnetically induced currents, and the other addressing why our planet is not fully covered by water, despite it passed through an extremely long ice era during its early evolution as a planet, thousands of millions of years ago. *Space Weather* refers to electromagnetic and particle conditions in the near-Earth near space. It is controlled by solar activity. The whole space weather chain extending from the Sun to the Earth's surface is very complicated and includes plasma physical processes, in which the interaction of the solar wind with the geomagnetic field plays an essential role. Space weather phenomena statistically follow the eleven-year sunspot cycle but large space weather storms can also occur during sunspot minima. Changes of currents in the Earth's magnetosphere and ionosphere during a space weather storm produce temporal variations of the geomagnetic field, i.e. geomagnetic disturbances and storms. Technological systems, even humans, in space and on the ground may experience adverse effects from space weather. At the Earth's surface, space weather manifests itself as "Geomagnetically Induced Currents" (GIC) in technological conductor networks, such as electric power transmission grids, oil and gas pipelines, telecommunication cables and railway circuits. Telecommunication systems have suffered from GIC problems several times in the past. In fact, a few years ago our telecommunication satellites network was severely affected by a very distance stellar explosion within our Galaxy. Optical fibre cables generally used today are not directly affected by space weather. However, metal wires lying in parallel with fibre cables are used to provide power to repeater stations, and they may be prone to GIC impacts. Trans-oceanic submarine communication cables are a special category regarding GIC since their lengths imply that the end-to-end voltages associated with GIC are very large. Many other technological structures lying on the Earth surface can be affected by GIC. Understanding this phenomenon, and envisioning solutions and prevention techniques is essential for the progress continued of our modern society, which depends so much on electric power supply. This chapter addresses in an extremely clear manner all the issues related to GIC. Meanwhile, the other chapter in this Section argues that if protoplanets formed from 10 to 20 kilometers in diameter planetesimals, in a runaway accretion process prior to the oligarchic growth into the terrestrial planets, then is logical to ask where these planetesimals may have formed in order to assess the initial composition of the Earth. By following a well-stablished scenario for describing such process the authors compute the efficiency factor for the formation of planetesimals from the pre-solar system nebula, to then using such factor to compute, as a function of the nebula mass, the feeding zones that contributed to material contained within 10, 15 and 20 kilometers in diameter planetesimals at a distance of about 1. A.U. from the Sun. Upon selecting reasonable nebula masses, the planetesimals contain a minimum of 3% water as ice by mass. The fraction of ice increases as the planetesimals enlarge in size and as the nebula mass decreases, since both factors increase the feeding zones from which solids in the planetesimals are drawn. In virtue of this estimate, a couple of questions are raised: Is there really a problem with the current scenario which makes the Earth too dry? Or, is it possible that the nascent Earth lost significant quantities of water in the final stages of accretion till reaching its late (to the present) configuration. The answer found by the authors to those queries appears to suggest that such a transition indeed took place.

X Preface

to succeed in such adventure out there.

recalls that the activities of nations involved in the exploration and use of the outer space is governed by the *Outer Space Treaty,* which defines basic principles for using the outer space. Despite the *Treaty* states that "The exploration and use of outer space shall be carried out for the benefit and in the interests of all States", until recent years space exploration was a privilege of a few countries (United States, Japan, Europe and Russian Federation), which managed to develop the technologies necessary to adventure far out of our planet. This chapter discusses extensively a very innovative and recently introduced concept in this field: *the democratization of the space*. Countries wanting to use the space for the good of their citizens and to boost their development stepped into the space technology arena. In the late years China and India made great achievements. As of today, these countries managed to put their own launch vehicles on serial production and even reached lunar orbit. Meanwhile, late industrialized nations like Brazil, South Africa, Turkey, Thailand, Malaysia and some other countries had their first steps mostly through relatively low-cost small satellite technology transfer programs based on technological partnerships with the countries strong in technology for navigation through the solar system. The chapter ends up by listing the set of technological requirements that countries newcomers into outer space research needs to accomplish, and stresses the large investments (man-power and financial) that are expected in order

Section II focuses on the evolution of our planet. It offers a couple of articles. One discusses the effects on the ground due to geomagnetically induced currents, and the other addressing why our planet is not fully covered by water, despite it passed through an extremely long ice era during its early evolution as a planet, thousands of millions of years ago. *Space Weather* refers to electromagnetic and particle conditions in the near-Earth near space. It is controlled by solar activity. The whole space weather chain extending from the Sun to the Earth's surface is very complicated and includes plasma physical processes, in which the interaction of the solar wind with the geomagnetic field plays an essential role. Space weather phenomena statistically follow the eleven-year sunspot cycle but large space weather storms can also occur during sunspot minima. Changes of currents in the Earth's magnetosphere and ionosphere during a space weather storm produce temporal variations of the geomagnetic field, i.e. geomagnetic disturbances and storms. Technological systems, even humans, in space and on the ground may experience adverse effects from space weather. At the Earth's surface, space weather manifests itself as "Geomagnetically Induced Currents" (GIC) in technological conductor networks, such as electric power transmission grids, oil and gas pipelines, telecommunication cables and railway circuits. Telecommunication systems have suffered from GIC problems several times in the past. In fact, a few years ago our telecommunication satellites network was severely affected by a very distance stellar explosion within our Galaxy. Optical fibre cables generally used today are not directly affected by space weather. However, metal wires lying in parallel with fibre cables are used to provide power to repeater stations, and they may be prone to GIC impacts. Trans-oceanic submarine

In Section III three articles are offered. One invokes the phenomenon of gravitational slingshot of planets to support an argument in favor of a new mechanism for featuring the evolution of the solar system. Planet fly-by, gravity assist is routinely used to boost the mission spacecrafts to explore the far reaches of our solar system. Voyager I and II used the boost provided by Jupiter to reach Uranus and Neptune. Cassini utilized 4 such assists to reach Saturn. A spacecraft which passes *behind* the moon gets an increase in its velocity (and orbital energy) relative to the primary body. In effect, the primary body launches the spacecraft on an outward spiral path. If the spacecraft flies *infront* of a moon, the speed and the orbital energy decreases. Traveling *above* and *below* a moon alters the direction modifying only the orientation (and angular momentum magnitude). Intermediate fly-by orientation change both energy and angular momentum. Accompanying these actions there are reciprocal reactions in the corresponding moon. The above slingshot effect takes place in a three body problem. In a three body configuration, the heaviest body is the primary body. With respect to the primary body the secondary system of two bodies is analyzed. In case of planet fly-by, the planet is the primary body and the moonspacecraft constitute the secondary system. While analyzing planetary satellites, the Sun is the primary body and the planet-satellite is the secondary system, although in the Keplerian approximate analysis implemented in such research, the Sun has been neglected without any loss of generality and without any loss of accuracy. This is a well understood method in astrodynamics. The *Basic Physics of the Gravitational Sling-Shot Mechanism* is that when there is considerable differential between Earth's spin velocity (ω) and Moon's orbital velocity (Ω) there is oscillatory changes in the tidal deformation of Earth and Moon. The tidally deformed shape oscillates between extreme oblateness (or stretching) to extreme prolateness (or squeezing). It is this rapid oscillation between the two extremes which leads to dissipation of energy and tidal heating because of the anelastic nature of Earth as well as Moon. This heating takes away energy from Moon's rotation. Moon's rotation slows down until its spin and orbital period are the same. Once spin and orbital periods are synchronized energy loss from Moon stops. This way the chapter offers to the reader a very reach analysis to reinforce its mainstream advocating for an alternative channel (with respect to the standard model for the solar system formation and evolution) for the evolution of the planetary and satellite dynamics, which had led to the present configuration in the solar system. The second article in this Section has as main goal to compare results generated by OrbFit with results presented by the CLOMON2 system which uses also the OrbFit software, and with the results of the JPL NASA SENTRY software, by focusing on how differently small effects in motion of the asteroid change impact solutions. It was possible thanks to public available source code of the OrbFit software. The orbital uncertainty of an asteroid is viewed as a cloud of possible orbits centered on the nominal solution, where density is greatest. This is represented by the multivariate Gaussian probability density and the use of this probability density relies on the assumption that the observational errors are Gaussian. For accomplishing this research the authors benefited of having at disposal the new version of the OrbFit software, v.4.2, which implements the new error model based upon a very recent research. The third article entitled: *Secular evolution of satellites by tidal effect* offers several significant and differentiated features. The article is extremely well structured, and elegantly presented, including the fashion in which the variables in the Y-axis of its Figure 1 are indicated. It is selfconsistently developed, and the astrodynamical motivation to readdress the tidal effects on the evolution of satellite systems is clear and well-supported by very appropriated references on the subject. The re-analisys of the dynamics of the system Neptune-Triton is of particular interest since it provides new insight on the system evolution if one implements not averaging of the equations of motion over the argument of the periastron, an approach that the author himself had presented in a previous research. Such approach renders important differences, particularly in the early evolution of such systems.

Preface XIII

radiation that can be expected to find if the physics needed to describe the electromagnetic interaction is nonlinear in the field, *F,* in the lagrangian of the theory. The CMB anisotropies detected by the Wilkinson Microwave Anisotropy Probe (WMAP) mission is of great importance in understanding the birth and evolution of the universe. However, by re-analyzing the WMAP raw data, the authors have found significantly different CMB results with respect to the WMAP official release, especially at the largest-scale structure detectable for the CMB quadrupole anisotropy, the l = 2 component. It was first shown the existence of such anomalies in the early released WMAP data, and then some basic principles of the WMAP raw data processing are given, which help to understand the problem under discussion. The analysis then shows the new CMB maps obtained from the same raw data, and explain in detail the difference between their result and the WMAP official one, and why the WMAP official release should be questioned. It is shown that the differences respect to WMAP are caused by a series of complex systematical effects, and thus it points out to what is still uncertain and needs to be addressed in future analysis. The consistent frame introduced by these authors stresses that some of the early discovered nomalies are still present, which suggests that perhaps for the issue of WMAP problems, they may have uncovered just a corner of the whole carpet. Based on this result, it is discussed why the reliability of, probably, all CMB detecting experiments is under questioning in virtue of such systematical effects. They conclude that it appears too early to claim presently about a closed (self-consistent) model for the Universe. Meanwhile, the other chapter stresses that WMAP and BOOMERanG experiments have recently set stringent constraints on the polarization angle of photons propagating in an expanding universe: Delta alpha =(-2.4 +/- 1.9 degrees. Having in mind such figures, the article proposes to study the polarization of the Cosmic Microwave Background radiation in the context of nonlinear electrodynamics (NLED), by using the Pagels-Tomboulis (PT) Lagrangian density, which uses a parameter featuring the non-Maxwellian character of the PT nonlinear description of the electromagnetic interaction. The polarization angle of photons propagating in a cosmological background with planar symmetry is then computed. After looking at the polarization components in the plane orthogonal to the direction of propagation of the CMB photons, the polarization angle is defined in terms of the eccentricity of the universe, a geometrical property whose evolution on cosmic time (from the last scattering surface to the present) is constrained by the strength of magnetic fields over extragalactic distances. The main result of this research suggests that the CMB polarization may be circular in nature, and that such feature can be discovered by

Finally, as the book editor, I can guarantee that the process of acceptance of each contribution to this book fully matches the InTech publication policy and further criteria from his own mind as editor. I am specially indebted to the book publishing manager, Ms. Romana Vukelic, for her permanent assistance, dedicated work and patience in handling with all the technical issues that enormously contributed to the

PLANCK satellite in the near feature.

The cosmology Section IV presents two articles addressing open issues in the understanding of the cosmic microwave background (CMB) radiation. One article argues on the way the data collected by WMAP, and other space missions, have been analized over the last years. The other chapter focuses on the imprint on the CMB radiation that can be expected to find if the physics needed to describe the electromagnetic interaction is nonlinear in the field, *F,* in the lagrangian of the theory. The CMB anisotropies detected by the Wilkinson Microwave Anisotropy Probe (WMAP) mission is of great importance in understanding the birth and evolution of the universe. However, by re-analyzing the WMAP raw data, the authors have found significantly different CMB results with respect to the WMAP official release, especially at the largest-scale structure detectable for the CMB quadrupole anisotropy, the l = 2 component. It was first shown the existence of such anomalies in the early released WMAP data, and then some basic principles of the WMAP raw data processing are given, which help to understand the problem under discussion. The analysis then shows the new CMB maps obtained from the same raw data, and explain in detail the difference between their result and the WMAP official one, and why the WMAP official release should be questioned. It is shown that the differences respect to WMAP are caused by a series of complex systematical effects, and thus it points out to what is still uncertain and needs to be addressed in future analysis. The consistent frame introduced by these authors stresses that some of the early discovered nomalies are still present, which suggests that perhaps for the issue of WMAP problems, they may have uncovered just a corner of the whole carpet. Based on this result, it is discussed why the reliability of, probably, all CMB detecting experiments is under questioning in virtue of such systematical effects. They conclude that it appears too early to claim presently about a closed (self-consistent) model for the Universe. Meanwhile, the other chapter stresses that WMAP and BOOMERanG experiments have recently set stringent constraints on the polarization angle of photons propagating in an expanding universe: Delta alpha =(-2.4 +/- 1.9 degrees. Having in mind such figures, the article proposes to study the polarization of the Cosmic Microwave Background radiation in the context of nonlinear electrodynamics (NLED), by using the Pagels-Tomboulis (PT) Lagrangian density, which uses a parameter featuring the non-Maxwellian character of the PT nonlinear description of the electromagnetic interaction. The polarization angle of photons propagating in a cosmological background with planar symmetry is then computed. After looking at the polarization components in the plane orthogonal to the direction of propagation of the CMB photons, the polarization angle is defined in terms of the eccentricity of the universe, a geometrical property whose evolution on cosmic time (from the last scattering surface to the present) is constrained by the strength of magnetic fields over extragalactic distances. The main result of this research suggests that the CMB polarization may be circular in nature, and that such feature can be discovered by PLANCK satellite in the near feature.

XII Preface

the early evolution of such systems.

the Keplerian approximate analysis implemented in such research, the Sun has been neglected without any loss of generality and without any loss of accuracy. This is a well understood method in astrodynamics. The *Basic Physics of the Gravitational Sling-Shot Mechanism* is that when there is considerable differential between Earth's spin velocity (ω) and Moon's orbital velocity (Ω) there is oscillatory changes in the tidal deformation of Earth and Moon. The tidally deformed shape oscillates between extreme oblateness (or stretching) to extreme prolateness (or squeezing). It is this rapid oscillation between the two extremes which leads to dissipation of energy and tidal heating because of the anelastic nature of Earth as well as Moon. This heating takes away energy from Moon's rotation. Moon's rotation slows down until its spin and orbital period are the same. Once spin and orbital periods are synchronized energy loss from Moon stops. This way the chapter offers to the reader a very reach analysis to reinforce its mainstream advocating for an alternative channel (with respect to the standard model for the solar system formation and evolution) for the evolution of the planetary and satellite dynamics, which had led to the present configuration in the solar system. The second article in this Section has as main goal to compare results generated by OrbFit with results presented by the CLOMON2 system which uses also the OrbFit software, and with the results of the JPL NASA SENTRY software, by focusing on how differently small effects in motion of the asteroid change impact solutions. It was possible thanks to public available source code of the OrbFit software. The orbital uncertainty of an asteroid is viewed as a cloud of possible orbits centered on the nominal solution, where density is greatest. This is represented by the multivariate Gaussian probability density and the use of this probability density relies on the assumption that the observational errors are Gaussian. For accomplishing this research the authors benefited of having at disposal the new version of the OrbFit software, v.4.2, which implements the new error model based upon a very recent research. The third article entitled: *Secular evolution of satellites by tidal effect* offers several significant and differentiated features. The article is extremely well structured, and elegantly presented, including the fashion in which the variables in the Y-axis of its Figure 1 are indicated. It is selfconsistently developed, and the astrodynamical motivation to readdress the tidal effects on the evolution of satellite systems is clear and well-supported by very appropriated references on the subject. The re-analisys of the dynamics of the system Neptune-Triton is of particular interest since it provides new insight on the system evolution if one implements not averaging of the equations of motion over the argument of the periastron, an approach that the author himself had presented in a previous research. Such approach renders important differences, particularly in

The cosmology Section IV presents two articles addressing open issues in the understanding of the cosmic microwave background (CMB) radiation. One article argues on the way the data collected by WMAP, and other space missions, have been analized over the last years. The other chapter focuses on the imprint on the CMB

Finally, as the book editor, I can guarantee that the process of acceptance of each contribution to this book fully matches the InTech publication policy and further criteria from his own mind as editor. I am specially indebted to the book publishing manager, Ms. Romana Vukelic, for her permanent assistance, dedicated work and patience in handling with all the technical issues that enormously contributed to the

#### XVI Preface

book final presentation. I also appreciate the work done by the book typesetter, and for the support received from the InTech Scientific Board, which helped to make it real this project.

> **Herman J. Mosquera Cuesta (Astrophysicist)**  Departamento de Física, Centro de Ciências Exatas e Tecnológicas (CCET), Universidade Estadual Vale do Acaraú, Brazil International Center for Relativistic Astrophysics Network (ICRANet), Italy Instituto de Cosmologia, Relatividade e Astrofísica (ICRA-BR), Centro Brasileiro de Pesquisas Físicas, Brazil International Institute for Theoretical Physics and High Mathematics Einstein-Galilei,

Italy


3. Conclusions

As the rate of the heat removal from the vapour increases, more condensate returns to the evaporator for another cycle. The effect of cooling water flow

thermosyphon heat pipe [19]. The heat input was fixed at 101 W while five different flow rates ranging from 0.00156 to 0.00611 kg/s were investigated. Temperature and the flow rate readings were recorded for each run and the effects of the cooling water flow rate were evaluated based on the overall thermal resistance, rate of heat transfer to the cooling water, outlet temperature of cooling water, performance of the thermosyphon, etc. The results from such work have shown that the performance of the pipe in terms of heat transfer to the cooling water increases with the increase in the cooling water flow rate. This is due to the mass flow of the cooling water which results in the enhancement of the rate of heat transfer from the pipe wall to the cooling

In addition to the general advantages of heat pipes, thermosyphon type is found to be highly durable, reliable and cost-effective, which make them useful for vari-

II.Liquid circulation: thermosyphon system is used for circulating liquids and volatile gases in heating and cooling systems such as water heaters, furnaces and boilers. It simplifies transfer of liquid or gas without using conventional

III.Cooling applications: thermosyphon is used in cooling of turbine blades, transformers, electronics, internal combustion engines and nuclear reactors [34, 35]. This is due to their ability to dissipate and transfer large amount of

IV.Aircraft cooling: due to their light weight, thermosyphon pipes are used in

rate at constant heat input was investigated on the performance of

Variation of the thermosyphon performance with inclination angle at different heat inputs [17, 19].

water and subsequent increase in the efficiency.

pump which adds cost and complexity to the system.

energy from small area without any significant loss.

2.6 Applications of thermosyphon

I.Solar heating of building [16].

cooling of aircraft and spacecraft.

ous applications, such as:

18

Figure 10.

Recent Advances in Heat Pipes

Several parameters affect the operation of thermosyphon such as fill ratio, working fluid, inclination, geometry, heat input, cooling water flow rate, etc. Experimental and numerical (CFD) studies are usually carried out to enable the investigation of the effects of some of these parameters on the performance of thermosyphon heat pipe for use in various engineering applications. Investigations on the effects of heat input, fill ratio, flow rate of cooling water on the temperature distributions on the wall of the pipe, overall thermal resistance and overall performance of the pipe at vertical orientation were shown to be possible both experimentally and using CFD. Also, the effect of inclination angle of thermosyphon on those parameters was successfully added in the Fluent. Hence, the chapter has shown that volume of fluid (VOF) model's approach in ANSYS together with UDF and other software can fully simulate the complex evaporation and condensation processes taking place in thermosyphon for both vertical and inclined orientations.

Recent Advances in Heat Pipes


**Oxidative Stress Increases Endogenous Complement-Dependent Inflammatory and Angiogenic Responses in Retinal Pigment Epithelial Cells Independently of Exogenous Complement Sources**

#### **Timon-Orest Trakkides 1, Nicole Schäfer 1, Maria Reichenthaler 1, Konstanze Kühn 1, Ricardo J. M. G. E. Brandwijk 2, Erik J. M. Toonen 2, Florian Urban 3, Joachim Wegener 3, Volker Enzmann 4 and Diana Pauly 1,\***

Received: 24 September 2019; Accepted: 11 November 2019; Published: 13 November 2019

**Abstract:** Oxidative stress-induced damage of the retinal pigment epithelium (RPE) and chronic inflammation have been suggested as major contributors to a range of retinal diseases. Here, we examined the effects of oxidative stress on endogenous complement components and proinflammatory and angiogenic responses in RPE cells. ARPE-19 cells exposed for 1–48 h to H2O2 had reduced cell–cell contact and increased markers for epithelial–mesenchymal transition but showed insignificant cell death. Stressed ARPE-19 cells increased the expression of complement receptors CR3 (subunit CD11b) and C5aR1. CD11b was colocalized with cell-derived complement protein C3, which was present in its activated form in ARPE-19 cells. C3, as well as its regulators complement factor H (CFH) and properdin, accumulated in the ARPE-19 cells after oxidative stress independently of external complement sources. This cell-associated complement accumulation was accompanied by increased *nlrp3* and *foxp3* expression and the subsequently enhanced secretion of proinflammatory and proangiogenic factors. The complement-associated ARPE-19 reaction to oxidative stress, which was independent of exogenous complement sources, was further augmented by the poly(ADP-ribose) polymerase (PARP) inhibitor olaparib. Our results indicate that ARPE-19 cell-derived complement proteins and receptors are involved in ARPE-19 cell homeostasis following oxidative stress and should be considered as targets for treatment development for retinal degeneration.

**Keywords:** oxidative stress; retinal pigment epithelial cells; complement system; inflammasome; foxp3; olaparib


*Edited by Sadia Vancauwenbergh*

Over the past decades, traditional academic library environments have transformed into digital libraries. This has resulted in many challenges for libraries in terms of the reinvention of libraries' roles and organizations, the skill sets of librarians, and library infrastructure. At the same time, this profound transformation has opened the door to many new avenues, such as the support and advancement of Open Science. This book offers insights into the transformation of traditional library environments to digital libraries and details how digital libraries can contribute to Open Science, in particular to Open Access, FAIR and Open Data, and Open Education, by describing methods, criteria, strengths, and weaknesses as well as applications.

ISBN 978-1-83968-200-1

Digital Libraries - Advancing Open Science

Published in London, UK © 2021 IntechOpen © PashaIgnatov / iStock


**3. Energy sources for mammalian spermatozoa**

Energy production requires easy availability of energy substrates. In a general sense, any eu‐ karyotic cell can obtain energy from either external or internal sources. External sources can be very different, from monosaccharides to lipids, whereas internal sources are mainly poly‐ saccharides such as glycogen and lipids, although other internal sources can be aminoacids and other. Regarding mammalian sperm, separate external and also internal energy sources

have been described, offering thus a view not radically different to that observed in other eukaryotic cells. Notwithstanding, there are several characteristics that differentiates mam‐ malian sperm to other eukaryotic cells in this point. Thus, the sequence of rapid location changes that underwent spermatozoa after ejaculation implies that they are synchronically placed in very separate locations inside female genital tract. This phenomenon will imply separate availability of external energy substrates, depending on the exact placement of spermatozoa. Moreover, the majority of cells integrated in a mammalian body will obtain their external energy sources directly from blood. This is not the case of spermatozoa, which are not keeping in direct contact with blood during their entire life. In this way, external en‐ ergy sources might came from secretions of cells from the female genital tract or from semi‐ nal plasma. This implies that sperm must have very efficient mechanisms to uptake external energy resources, which will not be directly directed towards them. Moreover, and center‐ ing on seminal plasma as energy source, the time lapse that ejaculated sperm are in close contact with seminal plasma is, in fact, short. In fact, in species in which the ejaculated vol‐ ume is short and rapidly placed inside a female genital tract of large size, like cow, contact between sperm and seminal plasma is very short, indeed. In any case, after ejaculation, both sperm and seminal plasma will immediately contact with secretions from the female genital tract. In this manner, sperm would be able to simultaneously find energy sources from both seminal plasma and the female genital tract. Only in species in which the volume of the ejac‐ ulate was very voluminous, like porcine, sperm will contact seminal plasma during a signifi‐ cant time lapse. Taking into account all of this information, it seems obvious that the adequate sperm external energy sources intake will depend of two main factors. The first factor will be the efficiency of external energy sources uptake mechanisms that sperm have developed. The second factor will be the specific mixture of external energy sources that sperm find in their journey inside the female genital tract. This mixture will came from both seminal plasma and female genital tract secretions, with predominance from one or the oth‐ er source depending on the species and the exact location inside the genital tract.

the sperm motion by itself. This drop in energy requirements will be surely linked to a change in energy-fuelling pathways, although at this moment the changes suffered by ener‐

However, this is not the last change that mammalian sperm metabolism has to suffer in their life time. Once sperm reach oviduct, they rest in the oviductal crypts until their re-activa‐ tion, following ovulation. This resting step is of the utmost importance, since at this point sperm, in tightly contact with oviductal cells, reach full capacitated status [14, 55]. Capacita‐ tion implies a myriad of functional and structural changes, like loss of cell membrane cho‐ lesterol, increase in tyrosine, serine and threonine phosphorylation levels of a wide array of separate proteins and intracellular calcium mobilization, whose full description is not possi‐ ble in this chapter (see [52, 53] as reviews). Capacitation, however, has a great interest in the sense that its full achievement again implies new energy requirements to carry out processes like the increase in tyrosine phosphorylation of specific sperm proteins, such as pro-acrosin [13, 19]. This new requirements will imply again new changes in energy metabolism, which will be closely linked to the progressive changes that sperm function must suffer during this

Finally, remnant sperm will be loaded from the oviductal crypts in order to undergo oocyte penetration. In this period, capacitated sperm adopt a totally specific motility pattern known as hyperactivated motility, with separate characteristics depending on the studied species [51]. Once reached the oocyte, sperm have to penetrate it, launching a series of energy-consuming processes like adherence to oocyte zona pellucida and subsequent acrosome exocytosis [29]. Again, energy requirements will change when comparing with other sperm life–span steps. In this sense, acrosome exocytosis will need a fast and intense energy burst and, in fact, it has been described that progesterone-induced acrosome exocytosis in boar sperm that were pre‐ viously subjected to "in vitro" capacitation is simultaneous to an intense and transitory in‐ crease in O2 consumption, which would correspond to transitory mitochondria activation [43]. What are the main conclusions that can be yielded? The basic conclusion from all of this in‐ formation would be that the dramatic changes that undergo mammalian spermatozoa from ejaculation to oocyte penetration must be accompanied by concomitant, dramatic changes in their energy regulating mechanisms. Little is known regarding how mammalian sperm modulate these changes, and this is one of the most challenging investigation fields that is

Energy production requires easy availability of energy substrates. In a general sense, any eu‐ karyotic cell can obtain energy from either external or internal sources. External sources can be very different, from monosaccharides to lipids, whereas internal sources are mainly poly‐ saccharides such as glycogen and lipids, although other internal sources can be aminoacids and other. Regarding mammalian sperm, separate external and also internal energy sources

gy metabolism during this step are not well known.

156 Success in Artificial Insemination - Quality of Semen and Diagnostics Employed

currently open in the study of mammalian sperm function.

**3. Energy sources for mammalian spermatozoa**

period.

All of this digression has been only centered in the origin of sperm external energy sources. However, what are exactly these energy sources? There is a general consensus in pointing at monosaccharides as the main energy sources for mammalian sperm [46]. Notwithstanding, sperm can utilize other substances than monosaccharides. Thus, boar sperm is able to utilize a wide range of substances, such as glycerol, lactate, pyruvate and citrate [26, 27, 37]. Other species are able to utilize also non-monosaccharide substrates as energy sources, although more information is needed to clarify this point (see as examples [22, 50]). The utilization of non-monosaccharide substrates as energy sources raises the question of the usefulness of these substrates. It has been suggested that these substrates could be an alternative in cir‐ cumstances in which monosaccharide availability was limited [27, 37]. However, a thorough study of the energy substrates content that is present in each segment of the female genital tract is lacking, even in the best studied species. This impedes the complete elucidation of this suggestion. Despite this, the role of non-monosaccharide substrates as external energy sources for mammalian spermatozoa deserves a more in-depth study in order to clarify its biological importance and role.

than that of mere energy sources. In this sense, incubation of dog sperm with fructose in‐ duced a specific decrease of serine phosphorylation levels of several proteins with key roles in the regulation of sperm cell function, such as protein kinases Akt, PI3 kinase, ERK-1 and protein kinase C ([17] and Figure 1). Strikingly, the incubation with glucose induced a spe‐ cific increase in the serine phosphorylation levels of other key regulatory proteins, like c-kit, Raf-1, tyrosine kinase and several protein phosphatases ([17] and Figure 1) These effects might induce sugar-specific changes in the overall dog sperm function. On the contrary, the incubation of boar sperm with either glucose or fructose did not induce any of the specific actions observed in dog sperm ([17] and Figure 1). All of these results clearly indicate that sugars can have a sugar- and species-specific action as signaling compounds, modulating thus sperm function in a closely-linked manner, depending on the moment in which sperm and sugar were kept in contact. In this way, the idea of seminal plasma sugars as mere ener‐ gy sources would be dismissed and being substituted by another idea; sugars as both energy sources and direct sperm function modulators in a simultaneous and coordinated form.

Energy Management of Mature Mammalian Spermatozoa

http://dx.doi.org/10.5772/51711

159

External sources, however, are not the only possibility found by mammalian sperm to ob‐ tain energy. Sperm can obtain energy also from endogenous sources. One of the most stud‐ ied sources is glycogen. The presence of a functional glycogen metabolism has been demonstrated in several species, such as dog, boar, horse, ram and bonnet monkey [5], al‐ though no glycogen was found in other species like mice and rat [3]. The primary role of these internal energy sources would be, logically, the maintenance of a limited energy reser‐ voir, although this could not be a universal function. In fact, dog sperm glycogen plays a role in the achievement of "in vitro" capacitation in a medium without glucose by being a key intermediate metabolite in the obtainment of energy through gluconeogenesis, which was essential to the achievement of the capacitated status [1, 2]. Thus, in dog sperm, glyco‐ gen plays an important role as capacitation regulator, besides its energy reservoir role. In this manner, a more in-depth sturdy of the exact role of glycogen should be needed to ob‐ tain a clearer picture of the utilization of endogenous substrates as energy sources in sperm.

**4. Main metabolic pathways to obtain energy and control mechanisms involved in the coordination of energy management of mammalian**

If monosaccharides are considered as the most important exogenous energy source for mammalian sperm, the question of the precise metabolic pathways by which mature mam‐ malian sperm obtain energy is relatively straightforward. Thus, the main metabolic pathway is glycolysis. The preeminence of glycolysis in freshly ejaculated sperm has been demon‐ strated in species like bull, mice and boar [21, 33, 39]. In fact, in species like boar, at least the 95% of the energy obtained from glucose is obtained through the glycolytic pathway in freshly obtained ejaculates [33]. The explanation of the glycolysis preeminence in these spe‐ cies is easy to understand. Glycolysis would reach high velocity rates taking from a very high velocity of sugars intake and phosphorylation. This will be due to the very high sensi‐

**sperm**

**Figure 1.** Mini-array analysis of the tyrosine, serine and threonine phosphorylation status of several proteins involved in the regulation of cell cycle and overall cell function in dog and boar spermatozoa after incubation with glucose or fructose. Dog and boar spermatozoa were incubated for 5 min in the absence (C-) or presence of either 10mM fruc‐ tose (10mM F) or 10mM glucose (10mM G). The tyrosine- (Phos-Tyr), serine- (Phos-Ser) and threonine-phosphorylation (Phos-Thre) levels of each spot in the mini-arrays were then analysed. The figure shows a representative image for five separate experiments. Figure excerpted from [17]).

Turning on monosaccharides, one of the most intriguing questions is the ability of sperm to utilize a variety of sugars that are present, at east in seminal plasma. As indicated above, this is a very difficult question to study, since the sugars composition of seminal plasma is very different among species. In this sense, there are a significant number of species in which fructose is the main sugar, like human or mice [32]. However, in other species, like boar, fructose is not predominant [6, 32]. The main sugar in horse is not fructose or glucose, but sorbitol [42]. This sorbitol is further converted in fructose through the action of the en‐ zyme sorbitol dehydrogenase, despite of old works indicating that horse sperm were not able to metabolize sorbitol [42]. Finally, there are also species, like dog, which lacks any monosaccharide in its seminal plasma [44, 48]. Another intriguing question is the mere pres‐ ence of sugars, like fructose and sorbitol that are not typical in any other animal tissue. In fact, both fructose and sorbitol are typical vegetal sugars, without any significant presence in animals, excepting in mammalian seminal plasma. It is noteworthy that the utilization of sugars like fructose, sorbitol and mannose by sperm of species like boar and dog of is in fact less effective in order to obtain energy than that of glucose [36, 45]. The greater effectiveness of glucose is mainly linked to a greater sensitivity to the hexokinase system, which phos‐ phorylates sugars as a first step in their metabolization pathway [36, 45]. Taking into ac‐ count this lower efficiency, it is difficult to understand the biological logics to utilize sugars like fructose or sorbitol as mere energy sources for sperm. Another explanation for this ap‐ parent contradiction would be that non-glucose monosaccharides could exert other roles than that of mere energy sources. In this sense, incubation of dog sperm with fructose in‐ duced a specific decrease of serine phosphorylation levels of several proteins with key roles in the regulation of sperm cell function, such as protein kinases Akt, PI3 kinase, ERK-1 and protein kinase C ([17] and Figure 1). Strikingly, the incubation with glucose induced a spe‐ cific increase in the serine phosphorylation levels of other key regulatory proteins, like c-kit, Raf-1, tyrosine kinase and several protein phosphatases ([17] and Figure 1) These effects might induce sugar-specific changes in the overall dog sperm function. On the contrary, the incubation of boar sperm with either glucose or fructose did not induce any of the specific actions observed in dog sperm ([17] and Figure 1). All of these results clearly indicate that sugars can have a sugar- and species-specific action as signaling compounds, modulating thus sperm function in a closely-linked manner, depending on the moment in which sperm and sugar were kept in contact. In this way, the idea of seminal plasma sugars as mere ener‐ gy sources would be dismissed and being substituted by another idea; sugars as both energy sources and direct sperm function modulators in a simultaneous and coordinated form.

External sources, however, are not the only possibility found by mammalian sperm to ob‐ tain energy. Sperm can obtain energy also from endogenous sources. One of the most stud‐ ied sources is glycogen. The presence of a functional glycogen metabolism has been demonstrated in several species, such as dog, boar, horse, ram and bonnet monkey [5], al‐ though no glycogen was found in other species like mice and rat [3]. The primary role of these internal energy sources would be, logically, the maintenance of a limited energy reser‐ voir, although this could not be a universal function. In fact, dog sperm glycogen plays a role in the achievement of "in vitro" capacitation in a medium without glucose by being a key intermediate metabolite in the obtainment of energy through gluconeogenesis, which was essential to the achievement of the capacitated status [1, 2]. Thus, in dog sperm, glyco‐ gen plays an important role as capacitation regulator, besides its energy reservoir role. In this manner, a more in-depth sturdy of the exact role of glycogen should be needed to ob‐ tain a clearer picture of the utilization of endogenous substrates as energy sources in sperm.

**Figure 1.** Mini-array analysis of the tyrosine, serine and threonine phosphorylation status of several proteins involved in the regulation of cell cycle and overall cell function in dog and boar spermatozoa after incubation with glucose or fructose. Dog and boar spermatozoa were incubated for 5 min in the absence (C-) or presence of either 10mM fruc‐ tose (10mM F) or 10mM glucose (10mM G). The tyrosine- (Phos-Tyr), serine- (Phos-Ser) and threonine-phosphorylation (Phos-Thre) levels of each spot in the mini-arrays were then analysed. The figure shows a representative image for five

Turning on monosaccharides, one of the most intriguing questions is the ability of sperm to utilize a variety of sugars that are present, at east in seminal plasma. As indicated above, this is a very difficult question to study, since the sugars composition of seminal plasma is very different among species. In this sense, there are a significant number of species in which fructose is the main sugar, like human or mice [32]. However, in other species, like boar, fructose is not predominant [6, 32]. The main sugar in horse is not fructose or glucose, but sorbitol [42]. This sorbitol is further converted in fructose through the action of the en‐ zyme sorbitol dehydrogenase, despite of old works indicating that horse sperm were not able to metabolize sorbitol [42]. Finally, there are also species, like dog, which lacks any monosaccharide in its seminal plasma [44, 48]. Another intriguing question is the mere pres‐ ence of sugars, like fructose and sorbitol that are not typical in any other animal tissue. In fact, both fructose and sorbitol are typical vegetal sugars, without any significant presence in animals, excepting in mammalian seminal plasma. It is noteworthy that the utilization of sugars like fructose, sorbitol and mannose by sperm of species like boar and dog of is in fact less effective in order to obtain energy than that of glucose [36, 45]. The greater effectiveness of glucose is mainly linked to a greater sensitivity to the hexokinase system, which phos‐ phorylates sugars as a first step in their metabolization pathway [36, 45]. Taking into ac‐ count this lower efficiency, it is difficult to understand the biological logics to utilize sugars like fructose or sorbitol as mere energy sources for sperm. Another explanation for this ap‐ parent contradiction would be that non-glucose monosaccharides could exert other roles

separate experiments. Figure excerpted from [17]).

158 Success in Artificial Insemination - Quality of Semen and Diagnostics Employed