Optimum Percentage Research Articles

Mapping forest cover and change as continuous variables is essential to advance consistency across forest monitoring products

ABSTRACT The rapid expansion of freely available Earth observation data, combined with advancements in forest monitoring capabilities, has led to the production of a variety of datasets on forest cover and change at the national and global scales. These datasets are essential for informing science and policy. Yet, this surge in available data products comes with the challenge of reconciling differences in the mapping of forest, non-forest, and forest loss across products. Differences in forest cover mapping between products result in divergent estimates of forest area change, potentially constraining the utility of these products to inform science and policy, consistently, across scales. We use the case of Colombia to demonstrate that these inconsistencies can be largely resolved by advancing operational forest monitoring capabilities toward the representation of forest cover and change as continuous rather than discrete variables. The analysis consisted of a comparison between the global forest change product (GFC) and the official national datasets on forest cover change for Colombia (IDEAM) in terms of overall and per-class classification agreement and estimates of forest-area loss. The comparison was performed after harmonizing the GFC dataset (HGFC) to maximize its overall classification agreement with the IDEAM map, based on the adoption of optimum percent tree cover thresholds, applied to GFC for subnational units. Based on these results, we evaluate whether classification agreement and disagreement between mapped forest and non-forest classes by HGFC and IDEAM can be explained by differences in continuous physical forest attributes, represented by forest Canopy Height (CH) and Above-Ground Biomass Density (AGBD). We produced the analysis for the entire country and also for mountainous and non-mountainous areas separately. We show that the optimal threshold in tree cover that maximizes map agreement, varies largely between subnational units, with values ranging between 20% and 100%. Results show a high overall agreement and also high agreement for stable forest and non-forest classes. Agreement between pixels classified as forest loss was much lower, regardless of the map used as reference. Classification agreement was lower for mountainous areas than for non-mountainous areas, particularly for forest loss and stable forest classes. Pixels representing classification disagreement were characterized by intermediate values of CH and AGBD that are significantly different from pixels classified as non-forest and forest for both maps, with significantly lower and higher CH and AGBD values, respectively. Differences were more notable in non-mountainous areas than in mountainous ones. We conclude that solving these large existing discrepancies in forest classification and forest loss estimates between datasets requires advancing operational capabilities toward the representation of forest cover and change as continuous rather than as categorical variables, with particular emphasis on mountainous areas. We illustrate how moving in such a direction can (1) promote consistency between forest cover definitions and map representation, (2) facilitate comparability among products and estimates of forest area loss at different scales of analysis, and (3) promote accountability in forest area loss assessments.

Identifying the Optimal Sugarcane Residue Percentage for Soil Enhancement: A Statistical and GIS Approach

Identifying the Optimal Sugarcane Residue Percentage for Soil Enhancement: A Statistical and GIS Approach

A targeted review on occurrence, remediation, and risk assessments of bisphenol A in Africa.

Bisphenol A (BPA) is a vital raw material used to manufacture various household and commercial goods. However, BPA is a contaminant of emerging concern (CEC) and an endocrine-disrupting chemical (EDC) capable of migrating and bio-accumulating in environmental and biological compartments. At threshold levels, they become toxic causing adverse health and environmental issues. BPA's occurrence in food, food contact materials (FCMs), beverages, water, cosmetics, consumer goods, soil, sediments, and human/biological fluids across Africa was outlined. Unlike most reviews, it further collated data on BPA remediation techniques, including the human and ecological risk assessment studies conducted across Africa. A systematic scrutiny of the major indexing databases was employed extracting relevant data for this study. Results reveal that only 10 out of 54 countries have researched BPA in Africa. BPA levels in water were the most investigated, whereas levels in cosmetics and consumer goods were the least studied. Maximum BPA concentrations found in Africa were 3,590,000ng/g (cosmetic and consumer goods), 154,820,000ng/g (soils), 189ng/mL (water), 1139ng/g (food), and 208.55ng/mL (biological fluids). The optimum percentage removal/degradation of BPA was within 70-100%. The potential health and ecological risk levels were assessed by comparing them with recommended limits and were found to fall within safe/low risks to unsafe/high risks. In conclusion, this study revealed that there is still little research on BPA in Africa. Levels detected in some matrices call for increased research, stricter health and environmental regulations, and surveillance.

Impact of plastic waste fiber and treated construction demolition waste on the durability and sustainability of concrete

This study explores the mechanical and durability properties of Plastic-Fibre Reinforced Concrete, incorporating hand-shredded plastic fibers sourced from polyethylene bags and PET bottles. Evaluations, including compressive and split tensile strength tests, were conducted on M40 grade mixes containing plastic fibers and 100% treated Construction and Demolition Waste (CDW), comparing them with conventional concrete. The results demonstrate a significant enhancement in strength properties with the addition of 0.25%, 0.5%, 0.75%, and 1% plastic-fibres, alongside the complete replacement of coarse aggregate with CDW, particularly noticeable at both 7 and 28-day curing ages. Although higher fiber dosages led to a slight reduction in compressive by 7% at the optimum percentage of 0.25% of PE and 0.5% of PET, the flexural strengths and split tensile strength exhibited a proportional increase of 11.7% and 18%. Surface analysis via Scanning Electron Microscopy (SEM) and elemental composition determination using Energy Dispersive Spectroscopy (EDS) revealed minimal fiber damage post-exposure, confirming its efficiency and contribution to higher strength and reduced weight loss in optimum mix. This novel approach combines manually recycled plastic waste as fibers with treated CDW, enhancing concrete properties while promoting sustainability. Sustainability analysis indicates that utilizing 100% CDW and plastic fiber contributes to reduced energy consumption, lower carbon emissions, and economic benefits. These findings underscore the potential of integrating non-degradable plastics into concrete mixtures, combined with treated CDW, offering both environmental sustainability and enhanced performance advantages in construction materials.

Study of the effect of N, N-diethyl hydroxyl amine/multi-layered graphene oxide hybrid on reducing cathodic delamination and increasing corrosion resistance of epoxy coating on steel substrate

In this study, a hybrid of multi-layered graphene oxide (MLGO) and oxygen absorbent corrosion inhibitor N, N-diethyl hydroxylamine (DEHA) was investigated. The nano hybrid was prepared in order to reduce the amount of cathodic delamination and increase the corrosion resistance of the epoxy coating. Epoxy coatings were prepared using the optimal percentage of 0.75 wt. % of the nano hybrid with different ratios between MLGO and DEHA like (1:2), (1:1) and (2:1). Mapping energy-dispersive X-ray spectroscopy, thermo gravimetry analysis and Fourier transform infrared (FT-IR) analysis indicated the uniform distribution of the inhibitor throughout the MLGO structure and the hydrogen bond interactions between them. The results of FT-IR spectroscopy: attenuated total reflectance test after six months confirmed the presence and stability of the inhibitor in the coating. Also, the results of 800 h of salt spray test and the long-term electrochemical impedance test after 7 months showed that the epoxy coating, containing MLGO-DEHA (1:2) had the highest corrosion resistance (2.54 × 107 Ω cm2) and the lowest cathodic delamination (15.9%). The results were also confirmed by cathodic delamination and pull-off adhesion tests.

Anisotropy and lateral compressive strength of large-size cement-stabilized macadam for bulging deformation resistance: A numerical analysis

Large-size cement-stabilized macadam (LCSM) base effectively hinders bulging deformation in asphalt pavements. Under vibratory compaction, the embedded skeleton structure and anisotropy of large-size aggregates (LSA) impact the mechanical properties of LCSM mixes. To reveal the mesostructure and anisotropy of LSA and determine the optimal volume percentage of LSA in LCSM mixes against bulging deformation, this study first characterized the bulging deformation resistance of LCSM mixes using lateral compressive strength (LCS). Next, the evolution of coordination number (CN) and distributions of contact force and contact normal for LSAs at different volume percentages under dynamic cyclic loading were investigated using the discrete element method (DEM). In particular, the induced anisotropic behavior was explored. Then, indoor tests and numerical simulations were conducted to assess the mixes’ LCS and vertical compressive strength (VCS); additionally, the compressive damage characteristics were analyzed. The results indicate that increasing the volume percentage of LSA and dynamic cyclic loading enhanced the CN, strong contact force, and contact normal density. LSAs at varying volume percentages exhibited pronounced anisotropic characteristics before and after loading, and the anisotropy factor of the LSA dropped after loading at a volume percentage of 65 %. Furthermore, the mixes’ VCS values exceeded LCS ones at the same LSA volume percentage, and there was a consistent relationship between the LSA anisotropy and the VCS/LCS ratio, suggesting that the optimal LSA volume percentage in LCSM mixes ranged from 60 % to 65 %. Finally, as the LSA volume increased, the skeleton effect became more pronounced than the interface attenuation effect, leading to higher VCS and LCS values in the mixes, thus improving their resistance to bulging deformation.

Influence of the basalt fibre and fly ash on the structural properties of sustainable high-strength concrete

Abstract The present article describes the experimental research carried out to investigate the properties of concrete containing basalt fibre reinforcement and concrete containing basalt fibres and fly ash additives. Each test was done as per Indian standards (IS-516). The experiments sought to establish both fresh and hardened concrete properties. In respect of new concrete, slump, setting time, bleeding, temperature, and density were estimated to check its quality. Compressive, flexural and split tensile strength are the three main parameters for assessing those qualities in a solidified state. It was determined that the utilization of fly ash with 20%, 30% or 40% proportions of cement involved resulted in a stronger concrete mixture. To these samples, different contents of basalt fibres 0.25%, 0.5%, and 0.75% by volume were added respectively. Standard samples were cast, cured and tested accordingly. Thus, the studies show that it is possible to mix concrete with basalt fibres without any segregation or balling effect on it or even sticking together during the mixing processes. Modestly increased splitting tensile and bending strengths have been obtained due to the introduction of basalt fibres on this composite material using which improved workability can be achieved more rapidly than conventional hydration reactions based solely upon Portland Cement chemistry, moreover, thermal stability has also been considerably enhanced, besides that even basic physical-chemical properties should be very much similar to those of ordinary Portland cement. Based materials thus ensuring better compatibility during processing from raw constituents towards final composites up-to-date with known technological aspects related specifically towards production practices carried out in developing countries like India. Such situations usually result primarily due to poor engineering control exercised over construction activities. Resulting problems areas namely joint locations limited access space between steel reinforcement bars inside walls. So often appearing weak points in overall design yield inadequate structural performance compared to intended specifications. Another reason why sustainable building methods cannot be fully adopted has been found that they lack proper skilled manpower despite having all necessary resources that are easily renewable. By compared with traditional ones made up of non-renewable sources such as fossil fuels. However, fly ash used in place of concrete only makes it harder without improving workability and strength at the optimum percentage.

Investigating alkali-activated concrete with recycled aggregate substitution in experimental research

Abstract In the present experimental investigation, a constant (optimum) percentage of GGBFS and fly ash in Alkali activated concrete (AAC) of M40 grade equivalent concrete. The natural aggregates are incorporated at percentages of 0.5 and 1.0 in the AAC composition. The studies indicate that Fly ash AAC demonstrates lower strength due to the necessity of heat curing for proper development, while the inclusion of Recycled Concrete Aggregate (RCA) leads to decreased compressive, split tensile, and flexural strengths, indicating a detrimental effect on mechanical properties. Despite slightly improved performance with 100% RCA content, it remains inferior to natural aggregates, attributed to adhered cement mortar potentially enhancing strength properties, which shows the need for further research to optimize mix designs and fully exploit the benefits of these alternative materials in AAC production.

Research of Shock Response Spectrum Prediction based on Machine Learning Method

Abstract Shock response spectrum (SRS) is the primary method of simulating explosive separation impact environment. SRS is obtained from shock experiments in traditional research, which consumes lots of materials. In this study, a prediction model based on machine learning (ML) is established to rapidly obtain SRS. 1053 sets of data obtained by shock experiments were used in the model. A total of 15 features are selected, in which 7 accelerations of different frequencies on the SRS are taken as target features. 7 types of ML algorithm are used for the prediction and the best one in each target is integrated in the completed model. The results indicate that the optimal average percentage errors at frequencies of 100Hz, 500Hz, 1000Hz, 3000Hz, 5000Hz, 7000Hz, and 10000Hz are 5.9%, 6.8%, 8.1%, 19.5%, 20.0%, 22.0%, and 19.7%, respectively. The error range of SRS fit by the 7 prediction targets is within ±20%. This study is contributed to improving the debugging efficiency of SRS.

Assessing the Usage of Barytes Powder and Cuddapah Stone Dust as Supplementary Cementitious Materials in Concrete of Grade M30 and M35

This research studied the effects of using Barytes powder and Cuddapah stone waste as substitutes for cement in M30 and M35 grade concrete using OPC. Cement production is known to harm the environment and consume a lot of energy, making the search for alternative materials to replace cement in concrete important.In this study, different amounts of Barytes powder and Cuddapah stone waste were added to concrete mixes as partial replacements for cement. The resulting concrete was tested for compressive strength and compared to normal concrete. The experiment involved making concrete samples with varying percentages of cement replacement, ranging from 0% to 50%, using Barytes powder, Cuddapah stone waste and Combination. The samples underwent standard curing and testing according to Indian standards.The research analysed the results to find the optimum percentage of cement replacement that provided satisfactory mechanical properties. This study determined the feasibility and effectiveness of using Barytes powder and Cuddapah stone waste as partial replacements for cement in concrete production.

Mechanical and Microstructural Properties of Environmentally Friendly Concrete Partially Replacing Aggregates with Recycled Rubber and Recycled PET

Today, waste generation is a worldwide problem, where the major source of waste is generated by worn-out tires and Polyethylene Terephthalate (PET) bottles. Therefore, as a way to provide an ecological disposal and reduce the environmental impact, the feasibility of producing ecological concrete (EC) with recycled rubber (RB) and PET as substitutes for natural aggregates is explored, determining their physical, mechanical and microstructural properties. This experimental study considered the replacement of fine aggregate with RB at 1%, 4%, 7%, 10%, 20% and 30%, and the optimum content of coarse aggregate plus the replacement of coarse aggregate with PET at 1%, 5%, 10% and 15%. The results showed that the optimum percentage of RB was 1%, which, when combined with PET, resulted that the design with 1% RB+ 1% PET was the optimum replacement combination, increasing 10% in bending, 1% in compression and for tension it decreased by 11%, in turn with the XRD test quartz and different aluminosilicates were found, such as portlandite and by SEM-EDS it was possible to visualize polymer flakes embedded in the analyzed fragment. It is concluded that RB and PET can be viable for the production of EC only if low percentages of replacement by natural aggregates are used.

Mechanical and Microstructural Properties of Environmentally Friendly Concrete Partially Replacing Aggregates with Recycled Rubber and Recycled PET

Today, waste generation is a worldwide problem, where the major source of waste is generated by worn-out tires and Polyethylene Terephthalate (PET) bottles. Therefore, as a way to provide an ecological disposal and reduce the environmental impact, the feasibility of producing ecological concrete (EC) with recycled rubber (RB) and PET as substitutes for natural aggregates is explored, determining their physical, mechanical and microstructural properties. This experimental study considered the replacement of fine aggregate with RB at 1%, 4%, 7%, 10%, 20% and 30%, and the optimum content of coarse aggregate plus the replacement of coarse aggregate with PET at 1%, 5%, 10% and 15%. The results showed that the optimum percentage of RB was 1%, which, when combined with PET, resulted that the design with 1% RB+ 1% PET was the optimum replacement combination, increasing 10% in bending, 1% in compression and for tension it decreased by 11%, in turn with the XRD test quartz and different aluminosilicates were found, such as portlandite and by SEM-EDS it was possible to visualize polymer flakes embedded in the analyzed fragment. It is concluded that RB and PET can be viable for the production of EC only if low percentages of replacement by natural aggregates are used.

Investigation of strength, durability, and microstructure properties of concrete with waste marble powder as a partial replacement of cement

Purpose Cement plays a significant part in concrete, and with the increasing demand for concrete, cement output varies day by day, allowing production to carbon dioxide emissions. As well as marble processing creates stone slurry and solid discards. These are often dumped irresponsibly on open land, polluting the soil. This improper disposal of marble waste is a major environmental concern. This study aims to propose a sustainable solution for reusing this waste material as a concrete additive. Design/methodology/approach A total of 135 concrete cubes of size 150 × 150 × 150 mm, 54 concrete cylinders of size 150 mm dia. and 300 mm height and 54 concrete beams of size 150 × 150 × 700 mm were cast. The replacement was 0%, 2.5%, 5%, 7.5%, 10%, 12.5%, 15%, 17.5% and 20% by weight of cement with marble dust to create M30 concrete with a water-cement ratio of 0.45. The test was performed to find the compressive strength (CS), flexural strength (FS) and split tensile strength. Also, durability tests like rapid chloride penetration test (RCPT), acid attack, ultrasonic pulse velocity (UPV) and water permeability test were performed. Findings After 7 and 28 days of curing, it was found that replacing 5% of cement with marble powder led to an initial strength improvement of up to 25% for both curing periods. However, further increases in marble dust resulted in an inconsistent decrease in strength for all the mixtures. Also, durability properties like acid attack test, water permeability test and RCPT, showed good performance at the optimum percentage of waste marble powder (WMP) as cement replacement. The microscopic analysis revealed a denser pore structure at lower WMP replacement levels, likely due to the powder filling in gaps. Originality/value This study reveals that by substituting 5% (optimum) of cement with WMP, there was CS improvement up to 8.4% and 17% for both 7 and 28 days of curing. WMP is typically finer than cement particles and fills the voids in the concrete more effectively, resulting best performance at optimum percentage against RCPT, UPV, acid attack and water permeability.

Stochastic optimal control of pre-exposure prophylaxis for HIV infection for a jump model.

We analyze a stochastic optimal control problem for the PReP vaccine in a model for the spread of HIV. To do so, we use a stochastic model for HIV/AIDS with PReP, where we include jumps in the model. This generalizes previous works in the field. First, we prove that there exists a positive, unique, global solution to the system of stochastic differential equations which makes up the model. Further, we introduce a stochastic control problem for dynamically choosing an optimal percentage of the population to receive PReP. By using the stochastic maximum principle, we derive an explicit expression for the stochastic optimal control. Furthermore, via a generalized Lagrange multiplier method in combination with the stochastic maximum principle, we study two types of budget constraints. We illustrate the results by numerical examples, both in the fixed control case and in the stochastic control case.

Wear performance of antibacterial dental composite with Salvadora persica extract and hydroxyapatite as fillers

AbstractThe characterization of S. persica (Salvadora persica) extract, which involved evaluating its antibacterial activity, demonstrated the extract's strong efficacy. Additionally, incorporating it into PMMA/HA showcased the composite's good antibacterial activity. The objective of this work is to evaluate how the incorporation of S. persica extract affects the wear resistance of the dental composite PMMA/HA, considering the critical importance of wear resistance in dental applications. The wear response of this biocomposite was tested against an Alumina ball using a pin‐on‐disc tribometer. Initially, the hydroxyapatite (HA) micro particles demonstrate a remarkable influence on wear behavior when incorporated at an optimal percentage (10%wt). This optimal inclusion rate not only significantly increases the wear rate but also instigates a shift in the wear mechanism, favoring abrasive wear while minimizing adhesive wear comparing to PMMA. The addition of the extract nanoparticles to the composite PMMA/HA decreases the wear rate except the composite containing 10 wt% of each filler. Additionally, it introduces adhesive wear, in addition to the existing fatigue and abrasion wear. Thus, the composite PMMA/HA could accommodate up to 10 wt% of the S. persica extract as the optimal percentage that provides antibacterial activity to this biocomposite without exhibiting a deterioration in wear performance.Highlights The evaluation of the effect of incorporating S. persica extract, which provides antibacterial activity, on the wear resistance of the PMMA/HA dental composite generally demonstrates a reduction in this property. The addition of S. persica extract introduces adhesive wear in addition to the fatigue and abrasion wear already present in the PMMA/HA composite. The composite PMMA/HA can accommodate up to 10 wt% of S. persica extract without compromising its wear performance.

Analisis Pengaruh Pasir Pantai Wahede Kabupaten Barru Terhadap Kuat Tekan Dan Tarik Belah Beton

Barru Regency is a coastal area with abundant potential for Wahede beach sand, which can be used to make economical concrete. This research aims to determine the compressive and tensile strength values of concrete as well as the optimal percentage of the beach sand mixture. The research was carried out at the Structure and Materials Laboratory of the Muhammadiyah University of Parepare, with a planned compressive strength of 20 MPa.The results of research on normal concrete compressive strength at 7 days were 12.27 MPa, 14 days 13.97 MPa, and 28 days 20.29 MPa. Variation: 25%; compressive strength: 7 days 13.58 MPa, 14 days 15.85 MPa, and 28 days 21.89 MPa. Variation 50%, compressive strength 7 days 14.34 MPa, 14 days 18.68 MPa, and 28 days 22.08 MPa. 100% variation, compressive strength: 7 days 14.72 MPa, 14 days 19.34 MPa, and 28 days 25.48 MPa. The split tensile strength of concrete decreases with an increasing percentage of beach sand: normal 28-day concrete 7,852 MPa, 25% variation 6,222 MPa, 50% variation 6,963 MPa, and 100% variation 8,000 MPa

A Probability-Based Model for Course Completion Prediction in Online Asynchronous Learning

The sheer scale of Massive Open Online Courses (MOOCs), presents a significant challenge in delivering personalized learning experiences and effective student support. With vast participation numbers, it becomes difficult for instructors to track individual progress, pinpoint specific areas where students struggle, and understand the underlying reasons for failure to complete the course. This lack of individualized attention can lead to disengagement and higher dropout rates. A probability-based analysis offers a solution by generating student-specific predictions about their likelihood of completion. This empowers educators to proactively identify those at risk, tailor interventions, optimize resource allocation, and potentially improve the overall learning experience within the MOOC environment. This study focuses on developing a robust predictive framework to accurately estimate the probability of students completing an introductory programming course offered on the Open Learning Platform of the University of Moratuwa, Sri Lanka. The approach began with a classification model to determine the likelihood of course completion. Building upon this, a regression model was developed to generate a specific probability percentage representing the chance of a student successfully completing the course within a designated time frame. Initial findings suggested that predictions from the classification model achieved the highest accuracy when students have completed approximately 42.8% of the course materials. It is anticipated that further refinements to the methodology will improve the reliability of the predictions. A crucial aspect of this research involves determining the optimal percentage of course progress needed to yield reliable probability predictions. This is investigated through systematic analysis and experimentations including incremental model testing. The dataset encompasses diverse demographic and educational variables, enabling the identification of influential factors affecting course completion. This study provides insights on developing personalized learning strategies, intervention tactics and academic planning within online asynchronous education.

Studying of Mechanical Behavior of Waste Materials Modified Cement Mortar

Large-scale environmental problems have been triggered by ceramic tiles from demolished buildings and animal bone waste. Therefore, optimizing their potential for reuse and recycling is an important goal of sustainable solid waste management. The primary objective of this study is to evaluate the feasibility of partial replacement of the fine aggregates in cement mortar with a combination of natural animal bone powder and industrial waste materials which is wall tiles ceramic powder. This study measures thermal and mechanical characteristics. Recycling construction waste is one of many ways to deny waste material from entering landfills and create new eco-friendly material that reduces energy consumption in buildings. Modified mortar cement specimens with 5% up to 25% mixtures were combined using a 1:3 ratio and a 0.5 W/C ratio to see how the ratios would affect the material’s properties. The addition of a superplasticizer boosted the cement mortar’s workability and compressive strength. The compressive strength, flexural strength, density, and thermal conductivity were evaluated for each mortar mixture ratio. Results showed that compared to regular cement mortar, cement mortar combined with 20% bone and ceramic powder wastes reached the optimal replacement percentage. Compressive strength increased by 54% and flexural strength by about 67%. At the 28-day mark, thermal insulation was lowered by 25%.It is concluded from this study that it is possible to use bone waste as a natural material with ceramic waste as an industrial material to modify the insulation and mechanical properties of cement mortar.

The role of nanomaterials in enhancing adhesion properties between bitumen and aggregate particles

During production and construction stages of asphalt mixtures, rheology of bitumen must be set at certain level. In addition, the adhesion strength between bitumen and the aggregate particles should be high enough so that during the service life of the pavement, asphalt mixture can resist various distresses. There are different methods of controlling rheological properties of bitumen binders and increasing adhesion properties of asphalt mixtures. One of the most effective methods of modifying bitumen binders of asphalt mixtures is using nanomaterials. In this research, two bitumen types of 60/70 and 85/100 penetration grades, three aggregate types (limestone, siliceous, and granite) and four nanomaterials; namely, nanohydrated lime (NHL), nanosilica (NSiO2), nanolime (NCaCO3) and, nanoclay bentonite (NClay) were used at 2, 4, and 6 % of the weight of bitumen. X-ray diffraction and X-ray fluorescence tests were performed and, microscopic images of thin-sections of aggregates and asphalt mixtures were taken with the aim of evaluating petrographic properties of aggregates and bonding characteristics of the bitumen binders with aggregate particles. Physical and rheological properties of the nano-modified bitumen binders were evaluated, performing dynamic shear rheometer and rotational viscometer tests. Boiling water and pull-off tests were also carried out in order to investigate the coating ability and the adhesion strength that is performed at the aggregate surface in the interface with the bitumen binders. Digital images were analyzed using Digimizer Software. The results indicated that the addition of nanomaterials at certain optimal percentage, affected viscosity and improved rheological behavior of bitumen binders at different temperatures; and, increase adhesion properties of the bitumen coating the aggregate particles. Comparing the effects of different aggregates, it resulted that the binder coating limestone aggregates performed better than the siliceous and the granite aggregates. Adhesion and rheological properties of the 60/70 pen bitumen that was modified with nanomaterials were better than those of the pure 85/100 pen bitumen. Nano-modified binders at 4 % NHL, or 2 % NSiO2, or 4 % NCaCO3, or 4 % NClay exhibited the best behavior. Among these, nano-modified binders containing 4 % NHL resulted in better performance. Finally, correlation between adhesion and rheological behavior of mixes were adequate for nano-modified binders in order to improve charcteristics of asphalt mixes at mixing operation and construction stages.

Zirconium-doped lead dioxide anodes prepared by sol-gel method for ampicillin removal from simulated pharmaceutical polluted wastewater.

New anodes consisting of zirconium-doped PbO2 coating, growth on titanium dioxide interlayer, were deposited on titanium substrates using spin coating method and have been tested for the removal of ampicillin, a β-lactam antibiotic, from water. Morphological, structural, and electrochemical properties of the prepared coatings were characterized by scanning electron microscopy (SEM), atomic force microscope (AFM), X-ray diffraction (XRD), and electrochemical impendence spectroscopy (EIS). Results showed that the incorporation of zirconium dopant had a noticeable modification in the morphology of anodes. An increase in the surface roughness and the specific active area were observed with Ti/TiO2/PbO2- 10% Zr electrode compared to other anodes. The electrochemical measurements indicated that the anode doped with 10% Zr showed a more protective coating performance than the undoped and 20% Zr-doped PbO2 electrodes. The experiments on ampicillin degradation revealed that doped lead dioxide anodes have excellent electrocatalytic activity. The major byproduct generated during anodic oxidation treatment has been identified as ampicilloic acid by liquid chromatography-mass spectroscopy (LC-MS) analysis. Results demonstrated that Ti/TiO2/PbO2- 10% Zr anode presents the best removal rate of ampicillin with a minimum intermediate amount, which leads to conclude that 10% is the optimum percentage of zirconium dopant for antibiotic wastewater treatment.