**5.3 Period of staggered phasing**

**Table 4** shows the various ways taken by the 10 schools studied to accommodate phasing in grades 8–11 when they returned to school. A closer examination of the data reveals that there were additional teaching time losses as a result of the phasing in grades 8–11, as will be seen. The incident occurred as the principals attempted to use the juggling effect to fit the remaining grades into the available classrooms. The majority of schools preferred the alternate and bi-weekly approaches, while one school employed a mixed strategy. Due to a lack of classrooms, the grades used an alternate strategy in which they alternated days in terms of class attendance. The biweekly model means that some of these grades would go to school for 1 week and then not return until the following week.

## **5.4 Assessment and revision plans**

The principals reported that the abrupt closure of schools on the 16th March 2020, disturbed some of the Term 1 assessments. Normally secondary schools would conduct extra tuition for a week during the end of the first term as part of their catch up and recovery programmes. After the partial reopening on the 8th of June for grade 12, the principals managed to finalise the Term 1 assessments to have a record of the results for purposes of the Continuous Assessment programme (CASS). At the time of conducting the face to face interviews with the principals, all

**Table 4.** *Staggered phasing models.*

#### *Cases of Principal Leadership Responses in a Volatile, Uncertain and Complex School… DOI: http://dx.doi.org/10.5772/intechopen.102852*

the secondary schools had just finished the Trial Examinations for grade 12 that were held in the last 2 weeks of September. It also meant that the principals were arranging the revision plans for grade 12 learners during the 1 week vacation as part of the catch-up and recovery programme. In all the 10 secondary schools the principals and Senior Management Teams were finalising the preplanning for both the internal and external assessments. By internal assessments we mean the final examinations for grades 8–11 and by external we mean the National Senior Examinations (NSC) for grade 12.

Social distancing had a knock-on effect on the types of examinations that schools required to prepare to fit the current grade, 12 students in 2020, into the available classrooms. The 2020 NSC examinations were unique in that due to the cancellation of the June Part-time NSC tests, part-time grade 12 learners and repeaters of grade 12 had to be accommodated at these adjacent schools for their examinations. According to all 10 principals, they were obligated to provide seats for three groups of students. The present grade 12 students, part-time students, and repeaters who required to write certain topics were divided into three groups. This created a lot of difficulties when it came to interpreting the schedule. Let alone the impact it had on an already tumultuous academic year caused by social isolation. The current NSC examinations were accommodated by principals for the final NSC tests.

The disruption led to some classes closing early to make room for these final exams. The early closure for grade 8–11 students also meant they were hardly getting enough time to be taught because they were either using the alternate or biweekly model. Five principals reported that they were bound to start grade 8–11 internal final examinations earlier than the requirements specified in the provincial circular. In other cases, the principals adopted the platoon technique due to adequate planning, which allowed some of these students to write in the afternoon sessions or alternately in the morning when the grade 12 NSC examinations were not seated according to the timetable. As a result, final internal evaluations for grades 8–11 were held in four secondary schools from early October to late October, before the start of the NSC final examinations on November 5th.

The disruptive effect it caused meant some of the classes needed to open the space for these final examinations, and therefore early closure for the grade 8–11 learners who hardly got enough time to be taught as they were either using the alternate or bi-weekly model. In the five secondary schools, the principals were bound to start early the internal final assessments for grades 8–11. In other instances due to proper planning, the principals used the platoon method, which meant some of these learners could write in the afternoon sessions or alternately in the morning when the grade 12 NSC examinations were not seated in terms of the timetable. As a result in four of the secondary schools, the final internal assessments for grades 8–11 were conducted early in October till late October before the commencement of the NSC final examinations on the 5th of November.

All 10 principals said they were juggling a lot of things and making a lot of adaptations to fit internal and external exams into the available learning spaces. Ulwezi school grade 11 students wrote the Isizulu and English Paper 1 and 2 earlier on the 7th and 8th of October to free up classroom space. As these were regarded to be language papers, this would allow teachers to complete their marking. The principle of Umbasa had written to the circuit manager, requesting that the grade 8 and 9 students be kept at home at the end of the third term to make room for grades 10–11 internal examinations. The principal at Umbasa wanted to make sure that grade 10–12 students shared lessons for both internal and external NSC exams.

At the time of some of the interviews, all 10 secondary schools had just completed the Trial Examination at the end of September, and teachers had just begun marking to provide feedback to students at the start of the fourth term. The input

and results of the trial exams for grade 12 students helped teachers plan and prepare focused areas that would impact revision plans for the 1 week of holiday. The grade 12 revision program, which began on October 26th and ended on October 30th, was designed by all 10 principals. This included attending Saturday courses as part of the final stretch of preparation for the final examinations, which began on the 5th of November and ended on the 15th of December. After grade 12 students had completed their exams, just nine secondary schools began a 3-week revision program.

As part of the ongoing catch-up programs, the principal of Uncwaba reported that two teachers were delivering Maths and Physical Science lessons at the Provincial Ukhozi Radio program. Uncwaba's principal was sure that the school would be able to make up for lost time and meet the goals set before the COVID-19 delays. The Undasa principal's grade 12 review technique was to divide students into groups based on their performance to prevent a one-size-fits-all approach that failed to address the risky students. The principals of Ulwezi and Uncwaba participated in networking, team teaching, and exchange programs to capitalise on the talents of the teachers, particularly in Math and Physical Science, respectively.

#### **5.5 Programs for a catch-up and recovery**

The principals only conducted the catch-up program as a final push before the final NSC examinations at nine schools. Because Zibandlela School did not have enough teachers for the other subjects, the grade 12 students were sent to Unhlaba School. The Mpumalanga Circuit's only rescue strategy was to keep the school open and avoid more problems with children who were unable to find teachers due to the PPN (**Table 5**).

**Table 5.** *School catch up programmes.*


**Author details**

Mauricio Corredor and Amalia Muñoz-Gómez\* Gebiomic Group, Faculty of Exact and Natural Sciences, University of Antioquia, Medellín, Colombia

\*Address all correspondence to<EMAIL_ADDRESS>
© 2020 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

**183**

*Pharmaceutical Antibiotics at a Significant Level in Nature: From Hospitals, Livestock…*

5053.

747-755.

Research and Public Health*,* 17(14),

[10] Díaz-Quiroz, C. A., Hernandez-Chavez, J. F., Ulloa-Mercado, G., Gortáres-Moroyoqui, P., Martínez-Macías, R., Meza-Escalante, E., & Serrano-Palacios, D. (2018). Simultaneous quantification of

antibiotics in wastewater from pig farms by capillary electrophoresis. Journal of Chromatography B, 1092, 386-393.

[11] Johnson, A. C., Keller, V., Dumont, E., & Sumpter, J. P. (2015). Assessing the concentrations and risks of toxicity from the antibiotics ciprofloxacin, sulfamethoxazole, trimethoprim and erythromycin in European rivers. Science of the Total Environment*,* 511,

[12] Lu, J., Wu, J., Zhang, C., Zhang, Y., Lin, Y., & Luo, Y. (2018). Occurrence, distribution, and ecological-health risks of selected antibiotics in coastal waters along the coastline of China. Science of the Total Environment*,* 644, 1469-1476.

[13] Paulus, G. K., Hornstra, L. M., Alygizakis, N., Slobodnik, J., Thomaidis, N., & Medema, G. (2019). The impact of on-site hospital wastewater treatment on the downstream communal wastewater system in terms of antibiotics and antibiotic resistance genes. International Journal of Hygiene and Environmental

Health*,* 222(4), 635-644.

[14] Davison, J., & Ammann, K. (2017). New GMO regulations for old:

[9] Ramessar, K., Peremarti, A., Gómez-Galera, S., Naqvi, S., Moralejo, M., Munoz, P., ... & Christou, P. (2007). Biosafety and risk assessment framework for selectable marker genes in transgenic crop plants: A case of the science not supporting the politics. Transgenic Research*,* 16(3), 261-280.

*DOI: http://dx.doi.org/10.5772/intechopen.95368*

[1] Davies, J. (2006). Are antibiotics naturally antibiotics? Journal of Industrial Microbiology and Biotechnology, 33(7), 496-499.

[2] Martínez, J. L. (2008). Antibiotics and antibiotic resistance genes in natural environments. Science,

[3] Shlaes, D. M. (2010). Resistance Chapter. The Perfect Storm. In *Antibiotics* (pp. 16). Springer,

[4] Aminov, R. I. (2009). The role of antibiotics and antibiotic resistance in nature. Environmental Microbiology,

[5] Rubin, R. P. (2007). A brief history of great discoveries in pharmacology: in celebration of the centennial anniversary of the founding of the American Society of Pharmacology and Experimental Therapeutics. Pharmacological Reviews*,* 59(4),

[6] Cromwell, G. L. (2002). Why and how antibiotics are used in swine production. Animal Biotechnology,

[7] Katakweba, A. A. S., Mtambo, M. M. A., Olsen, J. E., & Muhairwa, A. P. (2012). Awareness of human health risks associated with the use of antibiotics among livestock keepers and factors that contribute to selection of antibiotic resistance bacteria within livestock in Tanzania. Livestock Research for Rural Development*,*

[8] Manikandan, M., Chun, S., Kazibwe, Z., Gopal, J., Singh, U. B., & Oh, J. W. (2020). Phenomenal bombardment of antibiotic in poultry: Contemplating the environmental repercussions. International Journal of Environmental

*321*(5887), 365-367.

**References**

*11*(12), 2970-2988.

Dordrecht.

289-359.

13(1), 7-27.

24(10), 170.

*Pharmaceutical Antibiotics at a Significant Level in Nature: From Hospitals, Livestock… DOI: http://dx.doi.org/10.5772/intechopen.95368*


**7. Conclusions**

Despite numerous measures to improve the quality of the environment in the last decades, water quality is still seriously threatened by point and non-point sources of pollution. The application and development of ET for water protection, treatment and reuse in Slovenia have shown that they are appropriate measures for reaching EU regulations in terms of good water quality; moreover, they consider also the recycling of nutrients, reuse of water and potentially the production of biomass.

ET or ecoremediations mimic healthy natural ecosystems, have high buffer and self-cleaning capacity and contribute to habitat diversity. Moreover, these systems have the remediation ability, ensure high biodiversity and contribute to the stability of ecosystems. Nutrients and pollutants in ET are subdued to numerous processes that enable pollutant and nutrient transformations, degradation or stabilization. Through these processes, ET enable the reuse or recycling of nutrients as phosphorous and nitrogen, which nowadays have one way flow from consumption to waste, which will result in a shortage of plant fertilizers in a near future. Closing the loops of wastewater treatment is therefore crucial.

In Slovenia ET are in a rise since 1989. Different ET have been applied, namely treatment wetlands, watercourse revitalization, vegetated drainage ditches, waste stabilization ponds, phytoremediation of landfill sites. Most common ET in Slovenia are treatment wetlands for municipal sewage followed by watercourses revitalization. A high number of treatment wetlands indicate the priority of local communities and the authorities to solve deficient wastewater treatment systems in the country. An important part of the research and development of ET in Slovenia was focused also on the restoration of landfill sites, where a closed water and pollutant loop was investigated and successfully implemented; however, the system is not yet successful in the market because the local governance and environmental managers are still focused on wastewater treatment. Due to gradual acceptance and implementation of ET in local environments there is still a long way to walk in order to achieve sustainable society in terms of closing the loops of water and nutrient usage.

\*estimated numbers

212 Studies on Water Management Issues

Goričko on short sections of watercourses and lakes of eight local communities. Different in-stream and stream bank features were implemented to attain a successful revitalization. Weirs with small pools were constructed in the channels to improve streambed substrate, slow down the flow velocity, retain water and provide proper fish passages. Artificial indentations as well as restored and protected indentations contribute to better water habitats diversity. The passages for otters under the bridges were implemented which enabled otters to pass the roads safely. New vegetation zones (riparian wetlands and constructed wetlands) prevent erosion, provide buffer and better connectivity between terrestrial and aquatic ecosystems (Griessler Bulc & Šajn-Slak, 2009). The revitalization measures were also widely accepted by the local population, satisfied by the re-gained

natural appearance of the streams and water murmur.

Fig. 4. Schematic evolution of river revitalization (source: LIMNOS Ltd.)

Despite numerous measures to improve the quality of the environment in the last decades, water quality is still seriously threatened by point and non-point sources of pollution. The application and development of ET for water protection, treatment and reuse in Slovenia have shown that they are appropriate measures for reaching EU regulations in terms of good water quality; moreover, they consider also the recycling of nutrients, reuse of water

ET or ecoremediations mimic healthy natural ecosystems, have high buffer and self-cleaning capacity and contribute to habitat diversity. Moreover, these systems have the remediation ability, ensure high biodiversity and contribute to the stability of ecosystems. Nutrients and pollutants in ET are subdued to numerous processes that enable pollutant and nutrient transformations, degradation or stabilization. Through these processes, ET enable the reuse or recycling of nutrients as phosphorous and nitrogen, which nowadays have one way flow

**7. Conclusions**

and potentially the production of biomass.

Table 1. Data about ET in Slovenia

Ecosystem Technologies and Ecoremediation for Water Protection, Treatment and Reuse 215

Griessler Bulc, T. & Ojstrešek, A. (2008). The use of constructed wetland for dye-rich textile wastewater treatment. *J. hazard. mater*., June 2008, vol. 155, iss. 1/2, pp.76-82 Griessler Bulc, T. & Šajn-Slak, A. (2007). Agricultural run-off treatment with vegetated

Griessler Bulc, T. & Šajn-Slak, A. (2009). Ecoremediations - a new concept in multifunctional ecosystem technologies for environment protection. *Desalination*. 2-10 Griessler Bulc, T. (2006). Long term performance of a constructed wetland for landfill

Griessler Bulc, T.; Krivograd-Klemenčič, A. & Razinger, J. (2011). Vegetated ditches for

Griessler Bulc, T.; Zupančič-Justin, M. (2007). Sustainable solution for landfill leachate with a

Griessler Bulc; T., Istenič, D. & Krivograd-Klemenčič, A. (2010). The efficiency of a closed-

Grönlund, E.; Klang, A.; Falk, S. & Hanæus, J.(2004). Sustainability of wastewater treatment

Herzog, F.; Prasuhn, V.; Spiess, E.; Richner, W. (2008). Environmental cross-compliance

Hijosa-Valsero, M.; Matamoros, V.; Martín-Villacorta, J.; Bécares, E. & Bayona, J.M. (2010b).

Hijosa-Valsero, M.; Matamoros, V.; Sidrach-Cardona, R.; Martín-Villacorta, J.; Bécares,

Huang, T.L.; Ma, X.C.; Cong, H.B. & Chai, B.B. (2008). Microbial effects on phosphorous release in aquatic sediments. *Water Science and Technology*, 58, pp. 1285-1289 Hvitved-Jacobsen, T.; Johansen, N.B. & Yousef, Y.A. (1994). Treatment systems for urban

Iital, A.; Pachel, K.& Deelstra, J. (2008). Monitoring of diffuse pollution from agriculture to

Istenič, D.; Oblak, L. & Vrhovšek, D. (2009). Conditioning of drinking water on constructed wetland : elimination of Escherichia coli. *Ekológia (Bratisl.)*, 28, pp. 300-311

in small communities. *Water Research*, Vol. 44, No. 5, pp. 1429-1439

26th-29th June 2007. Padova: P.A.N., 2007, pp. 86-87

leachate treatment. *Ecol. eng*. 26, pp. 365-374

York: Nova Science Publishers, pp. 103-139

*Engineering*, Vol. 37, No. 6, pp. 873-882

principles. *Ecol. Eng*., 22, pp.155-174

*Policy,* 11, pp. 655-668

pp. 3669-3678

*Science & Policy,* 11, pp. 185-193

499-506

2011, vol. 63, no. 10, pp. 2353-2359

drainage ditches. V: BORIN, Maurizio (ur.), BACELLE, Sara (ur.). *Proceedings of the International Conference on Multi Functions of Wetland Systems*, Legnaro (Pd), Italy,

treatment of surface water with highly fluctuating water regime. *Water sci. technol*.,

use of phytoremediation. V: VELINNI, Albert A. (ur.). *Landfill research trends*. New

loop chemical-free water treatment system for cyprinid fish farms. *Ecological*

with microalgae in cold climate, evaluated with emergy and socio-ecological

mitigates nitrogen and phosphorus pollution from Swiss agriculture. *Env. Science &*

Assessment of full-scale natural systems for the removal of PPCPs from wastewater

E. & Bayona, J.M. (2010a). Comprehensive assessment of the design configuration of constructed wetlands for the removal of pharmaceuticals and personal care products from urban wastewaters. *Water Research*, Vol. 44, No.

and highway run-off in Denmark. *The Science of Total Environment*, 146/147, pp.

support implementation of the WFD and the Nitrate Directive in Estonia, *Env.*


*Article* **Performance Evaluation of Combined Hydrothermal-Mechanical Pretreatment of Lignocellulosic Biomass for Enzymatic Enhancement**

**Jiraporn Phojaroen 1 , Thitirat Jiradechakorn 1 , Suchata Kirdponpattara 1,2, Malinee Sriariyanun 2,3 , Jatupol Junthip 4 and Santi Chuetor 1,2,\***

**Abstract:** Pretreatment is a crucial process in a lignocellulosic biorefinery. Corncob is typically considered as a natural renewable carbon source to produce various bio-based products. This study aimed to evaluate the performance of the hydrothermal-mechanical pretreatment of corncob for biofuels and biochemical production. Corncob was first pretreated by liquid hot water (LHW) at different temperatures (140–180 ◦C) and duration (30, 60 min) and then subjected to centrifugal milling to produce bio-powders. To evaluate the performance of this combined pretreatment, the energy efficiency and waste generation were investigated. The results indicated that the maximum fermentable sugars (FS) were 0.488 g/g biomass obtained by LHW at 180 ◦C, 30 min. In order to evaluate the performance of this combined pretreatment, the energy efficiency and waste generation were 28.3 g of FS/kWh and 7.21 kg of waste/kg FS, respectively. These obtained results indicate that the combined hydrothermal-mechanical pretreatment was an effective pretreatment process to provide high energy efficiency and low waste generation to produce biofuels. In addition, the energy efficiency and waste generation will be useful indicators for process scaling-up into the industrial scale. This combined pretreatment could be a promising pretreatment technology for the production of biofuels and biochemicals from lignocellulosic valorization.

**Keywords:** hydrothermal-mechanical pretreatment; agricultural wastes; energy efficiency; waste generation


2.2.4. Empennage

According to Raymer [18], the empennage should typically be considered to be conventional. Nevertheless, unconventional tail configurations may have advantages in special use

cases. The criteria related to structural connections, dimensions, mass and flow interactions must be considered when deciding on the type of empennage [18].

Depending on the chosen propulsion concept, the yawing moment must be considered when designing the vertical tail plane (VTP). If the propulsion concept is not different from the reference aircraft, the empennage is dimensioned with a volume coefficient similar to the one of the reference aircraft. Since the configuration includes wingtip propellers, the volume coefficient of the VTP has to be increased to provide a sufficient yawing moment during wingtip engine failure. The increase is calibrated using the reference aircraft. First, the volume coefficient of the reference aircraft is determined. The ratio between the yawing moment created by the engine in the one engine inoperative (OEI) case and the volume coefficient of the VTP of the reference aircraft is calculated. This ratio is used to increase the conventionally calculated volume coefficient to account for the unconventional architecture.


**5. Conclusions and future perspectives**

Soybean is an important protein and oil seed crop and BNF is an important source of nitro‐ gen for the crop. Considerable work has been conducted regarding soybean proteomics, fa‐ cilitated by recent advancements in technology, but a more systematic approach to this method is required in order to understand the intricacies of plant growth and development in the face of interactions with various symbionts. There is wide variation in the ability of *B. japonicum* strains to fix atmospheric nitrogen and screening of the various strains known to us, in the light of specific agro-climatic conditions, will help improve effective BNF at a very low cost. In this regard, the proteomic profile can be of immense help in highlighting the protein-protein interactions that are involved during the process of nodule initiation, forma‐ tion and sustenance. This in-depth knowledge of the role of proteins in nodulation and plant growth promotion processes will assist in further improvement of soybean cultivars and their associated *B. japonicum* strains, for a better and more sustainable agriculture.


*Edited by Sonia Soloneski and Marcelo L. Larramendy*

This edited book, "*Genotoxicity and Mutagenicity - Mechanisms and Test Methods*", aims to present the latest developments from different fields, highlighting the detrimental influence that mutagenic and genotoxic agents inflict on DNA and how antimutagenic and anticarcinogenic modulators are able to reduce the negative impact of such toxic agents on living species.

ISBN 978-1-83880-041-3

Genotoxicity and Mutagenicity - Mechanisms and Test Methods

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


*3.2. Electronic Structure Topological Analysis on the Basis of Quantum Theory of Atoms in Molecules (QTAIM)*

Quantum theory of atoms in molecules (QTAIM) served as a method of choice to investigate the electronic properties of the studied molecules. The visualization and the results concerning the covalent and non-covalent interactions of the experimental and optimized structures of the studied dimers are presented in Table 2 and in Figure 7.

**Figure 6.** Potential of mean force (PMF) for the proton motion in the hydrogen bond of examined dimers with respect to the distance between the proton and its acceptor. (**D**) 2,6-difluorobenzamide and (**E**) 4-hydroxybenzoic acid.

**Table 2.** QTAIM-derived properties at BCPs for examined dimers from the structure deposited in the CCDC database and after geometry optimization at the *ω*B97XD/def2-TZVP level of theory. E1 is a bond energy based on the Espinosa model, given in kcal \* mol−1. Units of gathered quantities are as follows: electron density, *ρBCP*, is given in *e* · *a*−3 0 atomic units and the Laplacian of electron density, ∇2*ρBCP*, is in *e* · *a*−5 0 units. VBCP stands for BCP potential energy density and HBCP denotes the energy density at the BCP.

The use of the QTAIM method allowed a qualitative and quantitative description of the interactions between monomers. Bond energies were estimated on the basis of their linear dependence on the potential energy density at the BCP (VBCP) via the Espinosa equation [95]. It can be observed that, in the case of both (D) and (E) dimers, the hydrogen bonds form quasi-rings, which provides structural stabilization. Their formation is indicated by the presence of the ring critical points (RCPs) (marked as small yellow spheres in Figure 7). For the dimer denoted as (D1), the properties at BCPs corresponding to two non-covalent interactions and two covalent bonds: ND-H. . . OA hydrogen bond and the intramolecular F...N contact as well as the ND-H and C=OA bonds were analyzed extensively. Both aforementioned non-covalent interactions can be considered weak, rather electrostatic in nature, since their estimated bond energies lie below 4 kcal \* mol−1 and their Laplacian and energy density values are positive. Interestingly, when we inspect the data

corresponding to the (D2) dimer, it can be seen that the relaxation of the structure causes the weakening of ND-H covalent bond, the intramolecular F...N interaction (which is not even detected by QTAIM) and the accompanying strengthening of the ND-H. . . OA hydrogen bond. In this case, the character of the ND-H. . . OA is noticeably more covalent, because the corresponding *ρ* and energy density values become larger and lower, respectively (HBCP is indeed very close to zero) [34]. A similar analysis regarding the dimer (E) leads to the same conclusions: the optimization of the examined structures results in the strengthening of the hydrogen bond and the weakening of the corresponding covalent bond of the proton donor. More interesting is the characteristics of the hydrogen bond itself, namely OD-H. . . OA. In both the experimental and the optimized structures ((E1) and (E2)), the HBCP values corresponding to the hydrogen bonds are negative and their bond energies are much larger compared to (D1) and (D2)—for this reason, one can say that they are more covalent in nature than their counterparts, ND-H. . . OA.

**Figure 7.** QTAIM molecular graphs of the studied dimers. Ball and stick model was used for visualization. Bond paths, BCPs and RCPs are presented as green lines and small green and yellow spheres, respectively. Color coding: white—hydrogen, grey—carbon, red—oxygen, blue—nitrogen, yellow—fluorine. (**D1**,**E1**) are the experimental structures, whereas (**D2**,**E2**) are the structures after the relaxation at the *ω*B97XD/def2-TZVP level of theory.


**1. Introduction**

The service life of wood products in exterior applications is often limited by loss of appearance rather than loss of structural integrity [1]. As a result, there is a need for wood protection treatments to protect the appearance of the wood as well as against biodegradation by decay and insects. Weathering is a complex series of interactions between moisture, UV and visible light, oxygen, and surface-colonizing fungi [2]. Changes in color arise largely from the photo-degradation of lignin and the colonization by surface-inhabiting black-stain fungi [3].

A wide range of inorganic UV absorbers can be used to improve color stability [4]. This includes copper, which is already present in many residential preservative formulations. Copper-based wood preservatives are known to photo-stabilize lignin and slow the rate of surface degradation and color change from weathering [5–8]. One of the most widely used residential wood protection treatments in North America is micronized copper azole (MCA), which includes micronized basic copper carbonate (CuCO3·Cu(OH)2) (MBCC) as the primary biocide. Treatment with MBCC gives wood a pale blue/green color. Commercial products often add a colorant to give the MBCC-treated wood a more natural-looking brown color [9]. For exterior preserved wood, iron oxides dominate the market due to their low cost, the wide range of colors that are possible, their photo-protective effects, their compatibility with preservative formulations and their positive health and environmental profiles [10]. However, the color still fades over time.

It was observed that, in service, wood treated with copper-based preservatives tends to go from green/blue to a brown color as the surface of the wood oxidizes [11]. The use of peroxide to generate stable color complexes in wood impregnated with transitional metal compounds has been reported by Auger [12]. In the present work, we explored this approach using wood impregnated with MBCC followed by a peroxide post-treatment. The aim was to understand the e fficacy of this approach in yielding a brown, photo-stable wood surface with the potential to eliminate or reduce the need for the addition of colorants.

MBCC-treated wood with a peroxide post-treatment could potentially also a ffect preservative efficacy. MBCC has proven to be an e ffective wood preservative due to the slow solubilization of MBCC and reaction of this solubilized copper with the wood cell wall [13–15]. Oxidation of the wood surface was hypothesized to increase the amount of reacted copper, which could potentially increase biological e fficacy.

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

These experiments assess the performance of wood pressure-treated with MBCC, with and without a peroxide post-treatment. Specimens were evaluated for their resistance to color change and erosion following accelerated photo-degradation, and their resistance to disfigurement by artificially inoculated and incubated black-stain fungi under optimal conditions. An additional experiment examined the impact of the peroxide post-treatment on copper leaching and on the formation of reacted copper in the wood.

Red pine (*Pinus resinosa*) sapwood was used as a wood substrate throughout these experiments. MBCC was obtained from Timber Specialties Co. (Campbellville, ON, Canada). An iron oxide-based colorant formulation was used as a reference in the accelerated photo-degradation experiment. The MBCC and the iron oxide-based colorant were applied to wood by vacuum-pressure impregnation to target gauge concentrations of 4.0 kg of MBCC per cubic meter of wood and 2.0 kg of iron oxide-based colorant per cubic meter of wood, respectively.

The peroxide post-treatment consisted of a one-minute dip in a 20% solution of aqueous hydrogen peroxide adjusted to pH 6 with a dilute solution of sodium hydroxide at room temperature on air-dried samples. The 20% solution was prepared from a 30% hydrogen peroxide concentrate (Fisher Scientific, Ottawa, ON, Canada, ACS Reagent Grade). The conditions described above were determined based on a series of tests to optimize the peroxide treatment conditions. These tests are described in Appendix A. Factors evaluated included peroxide concentration, pH, storage time, drying and the impact of wood type (heartwood vs. sapwood).


*4.8. Statistical Analysis*

We investigated factors (public health features, clinical symptoms, coinfection with other pathogens) associated with a positive *G. duodenalis* result. The main dataset was constructed with data from one of the four sampling points—if the observation ever tested positive for *G. duodenalis*, we used data from the sampling point of the first positive *G. duodenalis* result; otherwise, we used data from the first sampling point in order.

We conducted Chi-squared tests (*p* < 0.05) to compare characteristics of cases and non-cases, and we calculated crude odds ratios (OR) with 95% confidence intervals (CI) to investigate the crude association between independent variables and a *G. duodenalis*positive result. We constructed multivariable logistic regression models to assess the association between *G. duodenalis* and (i) public health features and clinical signs or (ii)

coinfection with other intestinal pathogens, adjusted by age, tribe, and the number of samples. Additionally, we considered the serial results of *G. duodenalis* for observations with at least two samples. We conducted similar analyses by comparing those continuously negative versus continuously positive, and those discontinuously positive versus continuously positive.

Univariable analyses were conducted on all available observations, but observations with missing values were removed from multivariable analyses. All the independent variables were included in the analyses and we used the stepwise backward selection method, removing successively the least significant variable and using Akaike information criterion (AIC) and Bayesian information criterion (BIC) to construct the best fit model. Analyses were performed in R (package stats).

#### *4.9. Ethics Approval*

This study has been approved by the National Research Ethics Commission (CONEP), Ministry of Health (Brazil), under reference number 120/2008.


# **Catalytic Applications of Clay Minerals and Hydrotalcites**

Edited by Juan Cecilia and Carmen Pilar Jiménez Gómez Printed Edition of the Special Issue Published in *Catalysts*

www.mdpi.com/journal/catalysts


*2.1. Study Area*

Xuanwei County in Yunnan Province, Western China was selected as the study area. Xuanwei has a land area of 6502 km2, with a low-latitude highland monsoonal climate, average annual precipitation of 986 mm, and an average annual temperature of 13.3 ◦C. The area is located in the watershed zone between Yangtze River and Pearl River, which has a maximum elevation of 2868 m, a minimum elevation of 920 m, a relative altitude difference of 1948 m, numerous sloping fields, and few mountainous areas, and a relatively large slope gradient. The karst landform in the area spreads widely, with the outcrop reaching 3300 km2 and accounting for 52.74% of the entire land area of the county. The soil in the study area mainly consists of red earth and limestone. Xuanwei County is located in the "Hump Course" of World War II. The critical section of Yunnan–Burma, and Yunnan–Guizhou Highway played a significant role in the victory of the Allies during World War II (Figure 1). To guarantee smooth passage in this important transport corridor during the war, the U.S. army conducted several detailed works to study the geographical elements of the forests in this region, and the resulting historical military maps reflect the actual and ecological landscapes in the area during that period.

**Figure 1.** The maps of the location and main natural background of the study area. Note the following: (**a**) location; (**b**) elevation; (**c**) elevation classification; (**d**) slope grade; (**e**) soil type; (**f**) lithology. (We constructed this map using ArcGIS9.3 (http://www.esri.com/arcgis/about-arcgis) (accessed on 12 November 2021)).


*2.2.4 Willingness to use*

In the final section of the survey, parents were asked several questions to indicate their willingness to allow a teenager to use an AV in various contexts without a parent present. This included different destinations as well as different statuses of licensing, such as a learner's permit or a full license. As many parents have more than one child, questions were also posed to gauge willingness to allow younger children to ride with a teenager in an AV unaccompanied by an adult. Parents were then asked if they would prefer for their child to wait to learn to drive until they are older if AVs were a readily available alternative for them. The final question gave a brief explanation of a take-over request, which occurs when an AV needs competent human driver to take over the task of driving due to an unexpected situation [31]. They were then asked if they would feel comfortable letting their child ride unattended in an AV if take-over request training were included in the curriculum to get the learner's permit.


**Abbreviations**

electrospray ionization (ESI); atmospheric pressure photoionization (APPI); atmospheric pressure chemical ionization (APCI); high-resolution mass spectrometry (HRMS)**;** tandem mass spectrometry (MS/MS); gas chromatography/mass spectrometry (GC/MS); gas chromatography/nitrogen phosphorous detector (GC/NPD); gas chromatography/flame photometric detector (GC/FPD); collision-induced dissociation (CID); density functional theory (DFT).