Experimental Design Methodology Research Articles

Optimization of a Microencapsulation Process Using Oil-in-Water (O/W) Emulsion to Increase Thermal Stability of Sulforaphane.

Sulforaphane (SFN) is a bioactive compound widely studied for its potential applications in pharmaceutical, nutraceutical, and food industries since it offers health benefits due to its nature as a Phase 2 enzyme inducer. Its application in the food industry has been limited because SFN is unstable at high temperatures in an aqueous milieu. An option to increase SFN stability and protect it from thermal degradation is microencapsulation. The aim of this work was to optimize a microencapsulation process using oil-in-water emulsion to increase the thermal stability of SFN. The operation conditions that gave the highest entrapment efficiency were determined via experimental design and response surface methodology. Thermal degradation of microencapsulated SFN was studied at 37, 50, 60, and 70 °C. The optimum microencapsulation conditions were 8 min stirring, SFN/Gum Arabic ratio of 0.82, and surfactant/oil ratio of 1.0, resulting in an entrapment efficiency of 65%, which is the highest reported so far. The thermal stability of microencapsulated SFN was greatly enhanced compared with free SFN, with a 6-fold decrease in the degradation kinetic constant and a 41% increase in the activation energy. These results will contribute to a more efficient incorporation of SFN in various food matrices and explore new microencapsulation technologies to maximize the efficiency and stability of SFN.

Optimization of low-grade coal and refuse-derived fuel blends for improved co-combustion behavior in coal-fired power plants.

This study is aimed at utilizing three waste materials, i.e., solid refuse fuel (SRF), tire derived fuel (TDF), and sludge derived fuel (SDF), as eco-friendly alternatives to coal-only combustion in co-firing power plants. The contribution of waste materials is limited to ≤5% in the composition of the mixed fuel (coal + waste materials). Statistical experimental design and response surface methodology are employed to investigate the effect of mixed fuel composition (SRF, TDF, and SDF) on gross calorific value (GCV) and ash fusion temperature (AFT). A quadratic model is developed and statistically verified to apprehend mixed fuel constituents' individual and combined effects on GCV and AFT. Constrained optimization of fuel blend, i.e., GCV >1,250 kcal/kg and AFT >1,200 °C, using the polynomial models projected the fuel-blend containing 95% coal with 3.84% SRF, 0.35% TDF, and 0.81% SDF. The observed GCV of 5,307 kcal/kg and AFT of 1225 °C for the optimized blend were within 1% of the model predicted values, thereby establishing the robustness of the models. The findings from this study can foster sustainable economic development and zero CO2 emission objectives by optimizing the utilization of waste materials without compromising the GCV and AFT of the mixed fuels in coal-fired power plants.

Experimental and statistical investigation on structural feasibility of admixture based foam concrete with hexagonal wire mesh reinforcement

Foam concrete is an emerging construction material with reduced self-weight, high workability and improved thermal resistance. Deployment of this foam concrete for structural applications has not drawn keen attention of the research community. This study reports an investigation on the viability of using admixtures like, crumb rubber, silica fume and polypropylene fiber in foam concrete, reinforced with hexagonal wire mesh for enhanced strength and energy absorption. Taguchi's experiment design methodology was applied for assessment of the optimal mix of foam concrete with admixtures. Mixtures with three factors, namely silica fume, polypropylene fiber (PP fiber), and crumb rubber were developed in an L9 orthogonal array. Compressive and flexural strength parameters were used to establish the best possible mix proportions for maximum strength. Tests were conducted on hexagonal wire mesh (chicken mesh) kept in horizontal, vertical and horizontal with stirrup arrangements and the results were compared with control mix and the selected optimized mix. In all cases, percentage of steel reinforcement for the total volume of the concrete was kept as 1% by adjusting the layers of mesh provided. Based on the experimental results, crack and deflection patterns were analyzed and compared with the control specimen. The test results demonstrated enhanced strength and ductility of the foam concrete, buttressed by hexagonal wire steel mesh, as compared to control specimens. Besides, the reinforcement in the horizontal alignment with admixtures provided better strength and ductility with an enhancement of 130 % in flexural strength and a ductility index of 3.88 compared to control. Prognosis of the study advocated the propriety of using foam concrete as a structural member in construction.

Hydrothermal liquefaction of Elaeis guineensis trunks: Lessons learned from a case study in Guatemala

The oil palm industry has been under public scrutiny during the last decades due to environmental and social issues related to its practices. Oil palm (Elaeis guineensis Jacq.) trunks (OPTs) are of special interest as they are left idle in the field after the replanting process which is performed every 25 years. This common practice results in harvesting challenges, phytosanitary risks, and a loss of bioenergy potential. Due to their high moisture content and fibrous nature, OPTs present a problem for traditional conversion processes that require a dry and homogeneous material. This study evaluates the feasibility of converting OPTs into a bio-crude oil and biochar to increase the sustainability of the oil palm sector. To date, research efforts have primarily focused on hydrothermal liquefaction (HTL) of OPT without catalysts, resulting in a limited understanding of the potential of OPTs. Thus, the main novelty of this work is the evaluation of the effects of catalyst dosage (0–5 wt%) on the bio-oil yield, reaction temperature (260–300∘C), and residence time (15–60 min) using a half-fraction experimental design methodology. For this, OPTs extracted from two plantations in Guatemala were used. The maximum bio-oil yield (26.77 ± 3.60 wt%) was found at 260∘C for 15 min and 5 wt% catalyst with a high heating value (HHV) of 19.29 ± 1.33 MJ kg−1. Nonetheless, the bio-oils produced without a catalyst at 300∘C and 15 min have higher HHV (27.63 ± 1.35 MJ kg−1) and are similar to Diesel fuel based on their H/C and O/C ratio. These results indicate that there is a potential trade-off between the bio-crude oil mass yield and HHV when using the catalyst.

Optimization Studies on the Coagulation–Flocculation Process for PWW Treatment Using Cactus oputia Extract: Comparative Studies for Performance Evaluation

The treatment of Paint Waste Water, PWW is an important global issue for the minimization of water pollution especially in a developing country like Nigeria. The coagulation–flocculation process using Cactus Oputia Extract, COE as natural coagulant is reported for PWW treatment in the present study. The important process parameters pH, settling time, coagulant dosage and initial concentration were optimized using design of experiments (DOE). A full factorial composite experimental design and response surface methodology (RSM) were used to obtain the optimum values of the parameters. Also utilized in this study were Artificial Neural Network, ANN and Adaptive Neuro Fuzzy Inference System, ANFIS for performance evaluation. Using the numerical optimization technique of the design expert software, a combination of factors which concurrently fulfil the requirements placed on the response variable were determined. The best effluent removal efficiency was predicted to be 89.78% at the optimum values of the process parameters pH 6, settling time 30 mins, coagulant dosage 3 g and initial concentration 1.2 mg/l in this study.

Exploration of Novel Antibacterial and Anti-adhesive Formulations from three Chemically Characterized Essential oils: Optimization using experimental design methodology

In this study, experimental design approach coupled with MIC assay were used to determine the combined treatment effect of three Moroccan essential oils (EOs) derived from Ammi visnaga (AVEO), Mentha suaveolens (MSEO) and Lavandula stoechas (LSEO), against S. aureus, E. coli and P. aeruginosa, as well as to predict the optimal formulations of these EOs to inhibit bacterial adhesion on the stainless steel (304L SS) surface. EOs were obtained via hydrodistillation and then, their volatile content was analyzed using Gas Chromatography-Mass Spectrometry (GC–MS). The antibacterial activity was evaluated using disc-diffusion, microdilution assays. Moreover, the anti-adhesive effect was assessed using two complementary methods, including contact angle measurements and scanning electron microscopy (SEM) analysis. The GC-MS analysis revealed the presence of various bioactive compounds in AVEO, MSEO and LSEO. The main identified components were piperitenone oxide (52.04%) and pulegone (19.78%) for MSEO; and camphor (23.97 %) and menthol (21.5%) for LSEO. Whereas, AVEO was mainly characterized by the presence of linalool (30.24 %). The antibacterial assays showed that all EOs are able to inhibit the bacterial growth at low concentration (MIC ranged from 0.015 to 4 v/v (%)). The optimization of mixtures antibacterial effect has demonstrated the synergistic effect between the three EOs. The optimal mixture predicted against E. coli, P. aeruginosa, and S. aureus corresponded to 30%/42%/28%, 50%/50%/0%, 43%/30%/27%, and AVEO, LSEO and MSEO, respectively. The contact angle assessment indicated that LSEO, MSEO, AVEO and their optimal mixtures remarkably inhibit bacterial adhesion by the alteration of the physico-chemical properties of 304L SS surface. These results are confirmed by SEM analysis, and proved that EOs formulation was able to inhibit more than 80% of bacterial adhesion to 304L SS surface. In light of these findings, EOs mixtures recommended here, can be applied as a promoting and eco-friendly agent for combating the formation of biofilms on stainless steel surface.

Optimization of the physical properties of recycled plastic hybrid composites reinforced with rubberwood flour and crab shell flour for underwater use

This research aimed to optimize the composition and physical properties of recycled high-density polyethylene (rHDPE) hybrid composites reinforced with rubberwood flour (RWF) and crab shell flour (CS) for application in water immersion. The effects of composition and deterioration in physical properties after immersion in different water conditions (distilled water and seawater) were investigated. D-optimal mixture experimental design and response surface methodology were applied. The findings showed that all the physical properties deteriorated with an increase in immersion times. The increasing addition of CS increased the density, water absorption, thickness swelling, and surface roughness of the samples before and after being immersed in distilled water and seawater. Further, the results revealed that the optimal composition for application in water immersion included 60.0 wt% rHDPE, 29.5 wt% RWF, 5.6 wt% CS, 3.5 wt% maleic anhydride-grafted polyethylene, 0.5 wt% ultraviolet stabilizers, and 1.0 wt% lubricant with a desirability score value of 95.80 %. The predicted response of density, color measurement, surface roughness, water absorption, and thickness swelling were 0.89 g/cm3, 10.11, 4.59 µm, 10.27 %, and 7.73 %, respectively. Based on the findings in this research, the effective application of naturally sourced additives in composite products, and using the optimized rHDPE, RWF, and CS contents would enable the development of alternative materials for applications in water immersion.

RESPONSE SURFACE METHODOLOGY APPLIED TO ELECTRO-FENTON PROCESS FOR DEGRADATION OF RED BEMACID AS TEXTILE DYE MODEL

The textile industry produces persistent organic pollutants (POPs) that pose significant risks to ecosystems because of their toxic and hazardous nature. Consequently, there is an urgent requirement for the development of effective techniques to treat the effluents and remove these compounds. This work studied the viability of the Electro-Fenton (EF) process as a potential alternative for treating textile wastewater contaminated with POPs. A batch electrochemical reactor, equipped with a platinum grid cathode and stainless-steel sacrificial anode, was utilized to eliminate Red Bemacid (RB) dye. The study investigated the impact of four key operational parameters: (i) stirring speed (rpm), (ii) oxygen flow rate (L/min), (iii) supporting electrolyte concentration [Na2SO4] (mg/L), and (iv) current intensity (A), as well as their interactions on RB removal. To perform this, Central Composite Experimental Design (CCD) and Response Surface Methodology (RSM) were employed. Under optimized EF conditions for RB removal (stirring speed = 205.09 rpm, oxygen flow rate = 0.20 L/min, current intensity = 0.306 A, and supporting electrolyte concentration = 0.09 M), the EF process demonstrated exceptional removal efficiency, achieving approximately 94.51% removal of RB. The obtained results showed that the kinetic data of RB removal were in good agreement with the Behnajady-Modirshahla-Ghanbery (BMG) model. The CCD analysis revealed that the main effect of the current intensity had a significant impact on RB removal, as well as the interaction of all paired variables.

Optimum carbonization of Kevlar fabric for electromagnetic interference shielding applications

The study involved single-stage carbonization and physical activation of Kevlar woven fabric to convert into activated carbon fabric. The carbonization process was optimised for high carbon yield and low electrical resistivity of activated carbon fabric using Box-Behnken experimental design and response surface methodology. The three process parameters namely charcoal amount, gas flow rate, and carbonization temperature were selected. The empirical equations obtained through response surface methodology for carbon yield and electrical resistivity were found in good agreement with the experimental values. An optimum amount of charcoal, optimum nitrogen flowrate, and low carbonization temperature was found suitable for higher carbon yield. On the other hand, high charcoal amount, high carbonization temperature, and optimum nitrogen flow rate resulted in low electrical resistivity of activated carbon fabric. Later, the activated carbon fabrics were prepared under the optimum carbonization conditions to get high carbon yield and low electrical resistivity. The optimized sample for electrical resistivity showed higher electromagnetic interference (EMI) shielding properties at lower as well as higher frequencies due to its highly porous morphology and electrical conductivity.

Highly sensitive and selective electrochemical sensor for simultaneous determination of gallic acid, theophylline and caffeine using poly(l-proline) decorated carbon nanotubes in biological and food samples

In this work, a novel, simple and reproducible poly(l-proline)/functionalized multi-walled carbon nanotube composite on glassy carbon electrode (poly(PRO)-MWCNTs/GCE) was developed as an electrochemical sensor for the simultaneous determination of gallic acid (GA), theophylline (TP) and caffeine (CAF) by differential pulse voltammetry (DPV).The sensing platform was optimized by experimental design and response surface methodology, using various factors affecting polymerization and detection, such as electropolymerization time and potential, and pH, respectively. As a result, the dispersion conditions were the mixing of 1.78 mg MWCNTs with 1.00 mL l-proline solution to 4.14 mg mL−1 (in SDBS 0.5%), followed by 21 min of sonication with electropolymerization by 16 cyclic scans. In addition, the final analysis was performed at a pH of 3.00 and prior accumulation at 0.350 V for 40 s.The electrochemical behavior of GA, TP and CAF on the optimized sensor was investigated. As a result, the electrode preserves and synergistically combines the properties of each modifier. This new electrochemical sensor showed superior electrocatalytic properties for the oxidation of GA, TP and CAF, which significantly improved the sensitivity of the three compounds.Under the optimized experimental conditions, the detection limits achieved by S/N were 0.03, 0.04 and 0.11 μmol L−1 for GA, TP and CAF, respectively. The analysis of real samples was successfully performed in human breast milk, tea, infusion of yerba mate, coffee, Coca-Cola zero and energy drink, showing good recoveries, ranged between 87 and 108%. The proposed sensor also showed good selectivity, repeatability and reproducibility, indicating feasibility and reliability.This is the first time that the l-proline monomer is used as a dispersant for MWCNTs and as a precursor for the in-situ polymerization of the proline polymer. Previously, the electropolymerizations were carried out with the monomer in solution rather than as an exfoliant of MWCNTs, where the polymer is electrosynthesized between MWCNTs rather than on them. In this way, the large specific surface area and strong adsorption ability of the nanomaterial are enhanced, and the ability to promote electron transfer reaction is increased, which provides enough effective reaction sites.

Development of a new composite LDH/TiO2-3D for degradation of sulfaguanidine under UV and visible light: Experimental design, kinetic and mechanisms

Constructing 3D heterostructures has been considered an effective approach to enhance the photocatalytic activity of materials. However, the preparation of 3D heterostructures is always a complex process. In this paper, three-dimensional (3D) spherical TiO2 immobilized on Cu3AlCO3 Layered Double Hydroxides (LDH) was successfully synthesized using the impregnation method. The structure, morphology, and property of Cu3AlCO3-LDH/xTiO2-3D were investigated by X-ray diffraction (XRD), FTIR spectroscopy, scanning electron microscopy (SEM), energy dispersive X-ray (EDX), UV-Visible diffuse reflectance spectroscopy. The photocatalytic properties of composite materials were evaluated by degradation of sulfaguanidine (SGD) antibiotic under simulated solar irradiation. To optimize the photocatalysis process, an experimental design methodology was used. The experimental design utilized in most published works involves simple matrices that focus on quantitative factors. In contrast, our work enables the study of both qualitative factors (dissolved oxygen concentration) and quantitative factors (pH, catalyst dose and temperature) for both responses using a mixed matrix (D‐optimal) and a multiplicative model. To achieve this, 22 Run of experiments designed by the AZURAD® software. The optimal values of pH, catalyst dose, temperature, and dissolved oxygen concentration were found to be 8, 0.23 g.L−1, 25 °C, and 2 mg.L−1, respectively. The transformation product and possible degradation pathways of SGD were identified through Orbitrap LC/MS. Additionally, the present composite photocatalysts exhibited satisfactory re-usability for at least four cycles. Due to the facile synthesis process, higher photocatalytic activity under visible light irradiation and satisfactory re-usability, these composites can be considered as potential catalysts for degrading pharmaceutical pollutants in wastewater treatment.

Effects of WEDM and AWJ cutting methods on induction motor efficiency and total magnetic losses: Experimental design and response surface methodology

In this study, the effect of cutting electrical steel laminations using abrasive water jet (AWJ) and wire electrical discharge machining (WEDM) techniques on 5.5 kW induction motor efficiency (MEfficiency) and total magnetic losses (TLosses) was investigated. After the stator and rotor packages were formed, winding, varnishing and mechanical assembly processes were carried out and the motors were prepared for MEfficiency and TLosses tests according to the IEC 60034-2-1-1A standard. Tests were performed using different frequencies (f) and motor loading rates (MLoad). While burr formation was observed with the effect of plastic deformation on the cutting edge of electrical steels with AWJ, recast layer formation was observed with the effect of heat in WEDM. MEfficiency decreased while TLosses increased due to increasing f and MLoad in both cutting methods. Maximum MEfficiency and minimum TLosses values were measured in WEDM, it was determined that optimum results using Response Surface Methodology (RSM) were measured at f of 50 Hz and MLoad of 100% values in both cutting methods. The statistical effects of f and MLoad on MEfficiency and TLosses were revealed with ANOVA (Analysis of variance). In addition, mathematical models were developed for the prediction of MEfficiency and TLosses.

Optimization of an Acid-Catalyzed Direct Extraction-Methylation Method of Lipid Residues in Archaeological Vessels by Experimental Design and Response Surface Methodology

Optimization of an Acid-Catalyzed Direct Extraction-Methylation Method of Lipid Residues in Archaeological Vessels by Experimental Design and Response Surface Methodology

Application of Taguchi method and response surface methodology (RSM) for parametric optimization of natural convection heat transfer inside a triangular porous enclosure with in-line rectangular finned array

ABSTRACT Taguchi method is an experimental design methodology that uses a statistical technique to optimize process parameters while minimizing variability and improving output quality. In this article, Taguchi methodology has been utilized for parametric optimization of the design of a porous triangular enclosure, with an in-line rectangular finned array, to achieve maximum natural convection heat transfer. Three influencing parameters viz. fin spacing (S), percentage volume occupied (Vo) (measure of enclosure porosity), and fin tip to cooling plate distance (d), are optimized with consideration of maximizing the heat transfer (i.e. Nusselt number). The experimental design has been created using Taguchi’s L9 (3^3) orthogonal array. An analysis of variance (ANOVA) table, regression equation, response surfaces, and contour plots have also been generated using Response surface methodology, and the optimum values of influencing parameters have been suggested.

Solvent-Free Determination of Selected Polycyclic Aromatic Hydrocarbons in Plant Material Used for Food Supplements Preparation: Optimization of a Solid Phase Microextraction Method.

The exploitation of waste and by-products in various applications is becoming a cornerstone of the circular economy. A range of biomasses can be employed to produce food supplements. An example is a particular extract obtained from plant buds (rich in bioactive molecules), which can be easily retrieved from cities' pruning. In order to safely use this material, its possible contamination by organic pollutants needs to be estimated. A green and simple method to detect priority polycyclic aromatic hydrocarbons (PAHs) in bud samples by head space solid phase microextraction coupled to GC-MS was developed. This strategy, optimized through experimental design and response surface methodology, requires a minimal sample pre-treatment and negligible solvent consumption. The final method was found to be accurate and sensitive for PAHs with mass up to 228 Da. For these analytes, satisfactory figures of merit were achieved, with detection limits in the range 1-4 ng g-1, good inter-day precision (relative standard deviation in the range 4-11%), and satisfactory accuracy (88-105%), along with specificity guaranteed by the selected ion monitoring detection. The method was applied to bud samples coming from differently polluted areas, thus helping in estimating the safety of their use for the production of food supplements.

Experimental Investigation and Design Methodology of Built-Up I-Section Cold-Formed Steel Wall Panels with Sheathing under Axial Loading

Experimental Investigation and Design Methodology of Built-Up I-Section Cold-Formed Steel Wall Panels with Sheathing under Axial Loading

Optimal Experimental Design for the Assessment of Thermophysical Properties in Existing Building Walls

The estimation of wall thermal properties through an inverse problem procedure enables to increase the reliability of the model predictions for building energy efficiency. Nevertheless, it requires defining an experimental campaign to obtain in situ observations for existing buildings. The quality of the estimated parameter strongly depends on the quality of the experimental data used for the parameter identification. In other words, there is a close relation between the experiment design and the precision of the retrieved parameters. The design of experiments enables to search for the optimal measurement plan. It ensures the highest precision of the parameter to be estimated. For in situ measurement in buildings, the design of experiments seeks to answer the following questions: How many sensors do we need? What is the sensor position in the wall? The optimal experiment design methodology enables us to answer those questions. The unknown parameter is the thermal conductivity of wall façade model considering two-dimensional heat transfer induced by time and space varying boundary conditions.

Optimizing the First Step of the Biocatalytic Process for Green Leaf Volatiles Production: Lipase-Catalyzed Hydrolysis of Three Vegetable Oils.

Green leaf volatiles (GLVs), including short chain volatile aldehydes, are widely used in the flavor and food industries because of their fresh aroma. To meet the growing demand for natural GLVs with high added value, the use of biocatalytic processes appears as a relevant application. In such processes, vegetable oils are bioconverted into GLVs. First, the triacylglycerols of the oils are hydrolyzed by a lipase. Then, the free polyunsaturated fatty acids are converted by a lipoxygenase. Finally, volatile C6 or C9 aldehydes and 9- or 12-oxoacids are produced with a hydroperoxide lyase. Optimization of each biocatalytic step must be achieved to consider a scale-up. In this study, three oils (sunflower, hempseed, and linseed oils) and three lipases (Candida rugosa, Pseudomonas fluorescens, and Rhizomucor miehei lipases) have been tested to optimize the first step of the process. The experimental design and response surface methodology (RSM) were used to determine the optimal hydrolysis conditions for each oil. Five factors were considered, i.e., pH, temperature, reaction duration, enzyme load, and oil/aqueous ratio of the reaction mixture. Candida rugosa lipase was selected as the most efficient enzyme to achieve conversion of 96 ± 1.7%, 97.2 ± 3.8%, and 91.8 ± 3.2%, respectively, for sunflower, hempseed, and linseed oils under the defined optimized reaction conditions.

Beneficiation of andalusite ore by shaking table process using design of experiments methodology

ABSTRACT Andalusite is an alumina-silicate raw material, principally used in the manufacture of heat-resistant refractory products. In the present research, the andalusite mineral was successfully recovered from andalusite ore using a shaking table coupled with magnetic separation. The effects from shaking table parameters, that is deck tilt angle and water flow rate, on the alumina grade and andalusite mineral recovery were investigated using a design of the experiment (DOE), X-ray fluorescence (XRF), and X-ray diffraction (XRD). The results revealed that the deck tilt angle was the main influencing factor on the processing of andalusite ore. The application of a desirability function on the shaking table showed the increase of alumina content from 20.73 to 38.46 wt.% with a recovery rate of 80%. The recovered andalusite's grade fits the requirements for refractory product manufacturing.

Numerical analysis and optimization of adhesively-bonded single lap joints by adherend notching using a full factorial design of experiment

The objective of this study is to carry out experiments using the experimental design methodology to determine the optimal geometric configuration which improves the resistance of a single-lap joint with notched adherends subjected to uniaxial tensile load. On the sides of the adherends in contact with the adhesive layer, a longitudinal rectangular notch is introduced. A complete experimental design (15) of three factors at two levels: the adhesive thickness (tA), depth (dN) and extended length (LE) of the notch was used to determine their effects on strength of an adhesive joint. The response or dependent variable used was the resistance of a single lap joint (SLJ). Finite element (FE) analysis was conducted to investigate the effect of different notch parameters on the strength enhancement of the SLJs. A quadratic regression model with interaction is developed to relate the strength of an adhesive joint and the variables (tA, dN and LE). The regression model was validated using various statistical approaches. According to the ANOVA results, the model is highly significant and in good agreement with the experimental results. The quadratic regression model suggested was used for optimizing the resistance of the joint. The maximum joint strength occurs when the adhesive thickness is the smallest (left end) and when the adhesive thickness is the largest (right end) of the validated domain. The strength of SLJ increases when the notching parameters (dN and LE) increase in the validation zone. The numerical results show that to improve the resistance of an adhesive joint with notched adherend, it is necessary to minimize the thickness of the adhesive layer and to use notch with the highest depth and extension equal or greater than the overlap. The results show that using the adherend notching can significantly improve the load bearing capacity of SLJs.