Complete Factorial Design Research Articles

Recovery of Platinum and Palladium from Spent Automotive Catalysts: Study of a New Leaching System Using a Complete Factorial Design

The recovery of materials and energy from end-of-life products is increasingly a fundamental factor in the sustainable development of various countries. Recovering metals from different types of waste is not only a practice in support of the environment, but is also a profitable economic activity. For this reason, exhausted automotive catalysts can become renewable sources of critical raw materials such as Pt, Pd, and Rh. However, recovering Pt and Pd from spent catalysts through an efficient, economical, and green method remains a challenge. This article presents a new leaching process for the hydrometallurgical recovery of Pt and Pd from exhausted automotive catalysts. The leaching solution consists of an aqueous mixture of hydrochloric acid, two organic acids (citric acid and acetic acid) and hydrogen peroxide. A complete factorial plan on two levels (2k) was performed in order to evaluate the main effects of the analyzed factors and their interactions. The factors that were presumed to be the most influential on the leaching of Pt and Pd were the concentrations of the different reagents and the reaction time. The optimal circumstances for achieving the largest recovery (over 80% Pt and 100% Pd) were achieved using the following conditions: a concentration of HCl of 5 M, a concentration of H2O2 of 10% wt./vol., a concentration of C2H4O2 of 10%vol./vol., and a reaction time of 3 h.

Growth, laccase activity and role in 2,4-D degradation of Lentinus crinitus (L.) Fr. in a liquid medium

This study aimed to evaluate the role of L. crinitus laccase in the biotransformation of 2,4-D pesticide and the adsorption capacity and/or accumulation in the fungal biomass. Preliminary tests were carried out in liquid medium containing L. crinitus to detect the maximum concentration of 2,4-D in which the mycelium developed (5.025 g L−1). The growth and laccase activity for L. crinitus were analyzed using a complete factorial experimental design with variations in concentrations of glucose (16.65–33.35 g L−1), malt extract (0.825–9.175 g L−1), and 2,4-D (0.01–5 gL-1), and the mycelial samples were evaluated by SEM-EDS. The ability of L. crinitus to remove 2,4-D after 28 days was demonstrated by a decrease in concentrations of 2,4-D by up to 15.7% more than control treatments and occurred with both low (<2 g L−1) and high (>10 g L−1) glucose consumption conditions, reaching biomass concentrations below 2 g L−1, and presenting laccase activity between 3 and 6 g L−1. The laccase activity of the fungus depends on the initial amount of glucose and 2,4-D (up to 18 g L−1 and 4 g L−1). Lower concentrations of 2,4-DCP (0.01–2.70 mg L−1) may be an indicative of L. crinitus as its transformation agent. The presence of chlorine in the fungal mycelium (up to 4.0%) may represent its adsorption and/or accumulation by L. crinitus. L. crinitus can be described as a biotransformator of 2,4-D and 2,4-DCP through laccase activity, highlighting its potential for treatment of agricultural effluents.

Combined Ensiling of Tropical Beans and Sugarcane Stalks: Effects on Their Secondary Metabolites

In this study, the effect of mixed silage on the chemical composition, ensilability, in vitro cellulase digestibility and some of their plant secondary metabolites (PSM) were assessed. The lab-scale silage mixes were made in triplicate from sugarcane (Saccharum spp.) stalk and Canavalia ensiformis or Mucuna pruriens beans (Santa Clara, Cuba). Sugarcane stalks and beans were mixed at a ratio of 40:60 (on DM basis), respectively, in combination with a mixture of microbial inoculants (Lactobacillus acidophilus, and two Kluyveromyces fragilis strains, 4 × 105 colony forming units (CFU)/g of fresh matter). Before and after ensiling, the chemical composition, ensilability and contents of some PSM (trypsin inhibitor, L-canavanine, total tannins, L-dopa and phytic acid) were determined. A complete factorial design to assess the effect of the ensiling time (30, 60 or 90 days), the legume type (LT) and their interactions on the assessed parameters were performed. A better silage fermentation quality of the M. pruriens–sugarcane mixed material [e.g., lower (p &lt; 0.05) pH and ammonia N content and higher (p &lt; 0.05) concentration of lactic acid] was observed as compared with the C. ensiformis–sugarcane mixed material. The ensiling process reduced (p &lt; 0.001) the studied PSM, being higher (p &lt; 0.001) in the M. pruriens–sugarcane silages than in the C. ensiformis–sugarcane silages [trypsin inhibitor (86 vs. 76%); L-canavanine (70 vs. 53%); total tannins (54 vs. 50%); L-Dopa (89 vs. 86%)], except for phytic acid (65 vs. 68%), respectively]. It was concluded that ensiling enhances the quality of the feeds by predigestive reduction of the amount of secondary plant metabolites.

Brief research report: Photoplethysmography pulse sensors designed to detect human heart rates are ineffective at measuring horse heart rates

This study sought to evaluate the accuracy of a PPG (photoplethysmography) sensor designed to measure human heart rates in monitoring the distal limb pulse of healthy adult horses. We hypothesized that the PPG sensor is sensitive to placement location and orientation, and that measurement accuracies depend on placement and orientation on the limb. To evaluate this hypothesis, a completely randomized block design with a factorial treatment structure was used. Horses were considered as the block. Limb type (right front, left front, right hind, and left hind) and position of sensor (medial or lateral) were treatments, with levels arranged in a complete (4x2) factorial design. Data were collected by placing the PPG sensor on the limb of each horse (n = 6), with placement location according to the treatment (limb type and location) combination, and taking pulse readings for 60 seconds. Manual heart rates were collected concurrently using a stethoscope. Data were analyzed by calculating root mean square errors (RMSE) for the PPG measurements with the manual heart rates as a gold standard. Variation in RMSE associated with limb and location of sensor were evaluated using a general linear model with fixed effects for limb and location and a random effect for horse. Our results indicated that the PPG sensor was ineffective at measuring horse heart rates, and that the device was insensitive to placement location and orientation. Future work should focus on developing alternative analytics to interpret the data from PPG sensors to better reflect horse heart rates.

Subcritical water hydrolysis for the obtention of bioactive peptides from a grasshopper Sphenarium purpurascens protein concentrate

The effect of adding sodium bicarbonate(SB) and citric acid(CA) in the subcritical water (SW) hydrolysis process was studied to improve peptide extraction from Sphenarium purpurascens. A complete factorial(23) design was accomplished, and the effects of the temperature, pressure and modifier concentration on the degree of hydrolysis(DH), molecular distribution, antioxidant activity and Angiotensin I-converting enzyme(ACE) inhibitory activity were evaluated. A protein concentrate was obtained and hydrolyzed, showing a DH of up to 44.56 ± 0.92% with the addition of 1 M SB at 130 °C/20 MPa; meanwhile, 38.73 ± 0.58% was observed using CA under the same conditions. The best bioactivities were found in CA treatments: IC50 of up to 4.06 ± 0.35 mg/mL for DPPH, 330 ± 0.03 µg/mL for ABTS and up to 0.148 ± 0.016 mg/mL for the ACE inhibition activity. Moreover, differential hydrolysis was found due to the presence of modifiers and process conditions, being able to modulate the hydrolysis degree and obtaining hydrolysates with different characteristics and bioactivities.

Furrows and, to a Lesser Extent, Seed Priming Improve Restoration Success in the Sagebrush Steppe

Seeding of native perennial species commonly fails in the presence of invasive annual weeds. The ability of weeds to deplete soil moisture through early germination and rapid growth gives them a competitive advantage. A possible solution to help native species compete with weeds is to enhance their germination rate and growth. We primed seeds of bluebunch wheatgrass (Pseudoroegneria spicata) and Lewis flax (Linum lewisii) in a matrix of compost, clay, and biostimulants for 4−7 d. We used an extrusion technique to incorporate the seed and priming matrix into pellets for the priming duration that had the quickest germination. We evaluated primed seeds in pellets at two field sites against seeds in pellets that were not primed and seeds left untreated (control). Seed treatments were planted in shallow (1-cm) and deep (15-cm) furrows, in a complete factorial design, with the expectation that the deep furrow treatment would provide an enhanced microsite to improve plant growth. Results indicated that deep furrows were the strongest driver in enhancing seedling establishment, while priming showed a smaller contribution. In the first month after planting, a combination of priming and furrowing increased seedling emergence by 128% and 303%, for bluebunch wheatgrass and Lewis flax, respectively, compared with control seed planted in shallow furrows. The following year, primed bluebunch wheatgrass and Lewis flax seeds in deep furrows increased plant biomass by 158% and 110%, respectively, compared with control seed in shallow furrows. Overall, this study generally indicates that the rapid germination of primed seeds and the use of deep furrows may assist seedlings in establishing, which may allow them to better compete with invasive weeds.

Herbicidas dessecantes na antecipação da colheita e melhoria da qualidade de sementes de grão-de-bico

ABSTRACT Desiccating herbicides can promote uniformity of maturation, and early harvest and provide improvements in the physical, physiological, and sanitary seeds quality. The objective of this work was to evaluate the use of herbicides in early harvest and in the physiological quality of chickpea seeds. The experimental design was of randomized blocks with four replications, considering a complete factorial design with one control (no application) + two factors (four herbicides x three different doses): glufosinate-ammonium (200, 400 and 500 g a.i./ha); diquat (200, 400 and 500 g a.i./ha); carfentrazoneethyl (15, 30 and 37.5 g a.i./ha) and saflufenacil (49, 98 and 122.5 g a.i./ha). Saflufenacil (49 g a.i./ha) showed the lowest harvest anticipation (4 days) and a low percentage of vigor (50.25%). Glufosinate (400 g a.i./ha), was the most promising as it increased germination to 83.75% and vigor to 78.25%, in addition to promoting the anticipation of harvest by up to 17 days, while the normal cycle of the crop, observed in the control, was 154 days.

Aroma precursor enhancing in dried cocoa beans fermentation using enzyme and heat addition

&lt;abstract&gt; &lt;p&gt;Changes in amino acids and reducing sugars in cocoa beans during fermentation were investigated using a 3 × 3 full complete factorial design using different enzyme additions (cellulase, papain and control–no enzyme) and water bath temperatures (40, 45 and 50 ℃) as variables over three days of fermentation. Aroma precursors (reducing sugars and free amino acids) developed inside the bean by enzymatic mechanisms during fermentation are converted into volatile compounds such as pyrazines and aldehydes during roasting. This study aimed to improve the fermentation process of dried beans by adding acetic acid, heat and enzymes, because there is insufficient pulp for the ideal spontaneous fermentation process. Samples were analyzed for fermentation index, cut bean, reducing sugar amino acid composition and volatile aroma composition profile using headspace solid phase microextraction (HS-SPME) and gas chromatography mass spectrometry (GC-MS). The results showed that the fermentation index was significantly affected by the addition of enzymes and water temperature. Although amino acids rose to 200%–300%, the composition contained several acidic amino acids because the pH utilized less than 4. Adding cellulase enzymes increases the amount of reducing sugars and amino acids but does not result in the formation of various amino acids.&lt;/p&gt; &lt;/abstract&gt;

Development of directly compressible polyherbal tablets by using QbD approach a novel immunomodulatory material

A Quality by Design (QbD) strategy was used to develop and optimise a polyherbal tablet formulation in this study. Initial risk assessments of critical materials were conducted using the Risk Priority Number, and the effects of critical parameters (amount of microcrystalline cellulose and croscarmellose sodium) were proposed using a randomised complete factorial design. To further the findings, a Design of Experiments (DoE) approach was used to formulate four trial formulations, with independent variables of microcrystalline cellulose (MCC) 5 % -15 % and croscarmellose sodium (CCS) 0.5 % -5 %, and responses measured in friability and disintegration time, which were found to be 0.35–0.91 % and 11.4–15.5 minutes, respectively. Three formulations (F-1, F-2, and F-4) fulfilled the acceptable criteria and one formulation (F-1) had independent variables microcrystalline cellulose and croscarmellose sodium, out of four formulation trials (F-1 to F-4) were chosen for short-term stability study due to their better disintegration and friability profiles. The formulation factors X1: microcrystalline cellulose and X2: croscarmellose sodium were found to have a substantial impact on the responses Y1: Disintegration time (min) and Y2: Friability (%). This study proved that using quality by design to analyse quality characteristics and optimise polyherbal tablet formulation gives better results.

Simultaneous Voltammetric Determination of Non-Steroidal Anti-Inflammatory Drugs (NSAIDs) Using a Modified Carbon Paste Electrode and Chemometrics.

This work presents the simultaneous quantification of four non-steroidal anti-inflammatory drugs (NSAIDs), paracetamol, diclofenac, naproxen, and aspirin, in mixture solutions, by a laboratory-made working electrode based on carbon paste modified with multi-wall carbon nanotubes (MWCNT-CPE) and Differential Pulse Voltammetry (DPV). Preliminary electrochemical analysis was performed using cyclic voltammetry, and the sensor morphology was studied by scanning electronic microscopy and electrochemical impedance spectroscopy. The sample set ranging from 0.5 to 80 µmol L-1 was prepared using a complete factorial design (34) and considering some interferent species such as ascorbic acid, glucose, and sodium dodecyl sulfate to build the response model and an external randomly subset of samples within the experimental domain. A data compression strategy based on discrete wavelet transform was applied to handle voltammograms' complexity and high dimensionality. Afterward, Partial Least Square Regression (PLS) and Artificial Neural Networks (ANN) predicted the drug concentrations in the mixtures. PLS-adjusted models (n = 12) successfully predicted the concentration of paracetamol and diclofenac, achieving correlation values of R ≥ 0.9 (testing set). Meanwhile, the ANN model (four layers) obtained good prediction results, exhibiting R ≥ 0.968 for the four analyzed drugs (testing stage). Thus, an MWCNT-CPE electrode can be successfully used as a potential sensor for voltammetric determination and NSAID analysis.

Reference and target sample age distribution impacts between model types in dental developmental age estimation

The performance of age estimation methods may vary due to a combination of method- and sample-related factors. Method development and evaluation necessitates understanding what influences these factors have on age estimation outcomes. In the specific context of juvenile dental age estimation, we used a single dataset and complete factorial design to systematically test four potential sources of difference: age distributions of reference and target sample (uniform, unimodal, U-shaped), Bayesian (multivariate Bayesian cumulative probit) vs. classical regression modeling (multivariate adaptive regression splines i.e. MARS), and model selection bias. The dataset consisted of 850 sets of left mandibular molar scores from London children 5-18years old. True age and estimated age intervals in target samples were compared for bias, root-mean-squared error, precision, and accuracy using locally weighted smoothing of performance measures across the age range and means of performance metrics between factor-level combinations. We found interactions of model type, reference distribution, and target distribution. MARS models showed consistent evidence of age mimicry. Central tendency of the reference sample corresponded with increased bias while central tendency of the target sample corresponded with reduced RMSE and reduced precision for both model types. We found evidence of model selection bias, mitigated through averaging model metrics. We conclude that reference and target sample distribution influences and model selection bias are sufficient to cause difference in model performance within a single population. We suggest using Bayesian modeling, drawing uniform reference and target samples, and calculating test error on a hold-out sample to mitigate these challenges in method development.

Variables influencing the production of door jambs from Pinus taeda EGP panels

The influence of coverslip width and the physical arrangement of growth rings were studied relative to laterally glued Pinus taeda wood panels (EGP) used in the manufacture of door jambs, according to the requirements of ABNT-NBR 15.930 (2011). The goal was to determine the combination providing the best physical performance of the product. The experiments used the complete factorial design for two factors and four levels, i.e., 32, 56, 75, and 112 mm width coverslips, and rings arrangement of radial, tangential, cross coverslips, and ones with finger joints. A total of 48 EGP door jamb specimens (3 for each combination) measuring 2120 x 220 x 32 mm, with moisture content between 8% and 12% and apparent density between 400 and 600 kg.m-3 were used. Statistical analysis of variance (ANOVA) was used to investigate the influence of factors and their interactions on the following responses: visual aspect, moisture, density and dimensional (width and thickness) variations. It was found that both factors and their interactions influenced the level of significance of 1% on shape deviations. The best results were for panels produced with 32 and 56 mm coverslips, with cross or radial arrangement.

Physiological responses to lead and PEG-simulated drought stress in metallicolous and non-metallicolous Matthiola (Brassicaceae) species from Iran

• Lead increased levels of osmoprotectants and phenol compounds in the metallicolous Matthiola flavida . • Reduced root-to-shoot translocation and enhanced Pb accumulation in the root, under drought stress, is responsible for reduced toxic effects of Pb in the shoot of the metallicolous species . • Lead stimulates drought resistance in the metallicolous species by the accumulation of reducing sugars, phenolic compounds and antioxidant enzymes. Plants growing on quarry tailings at the Irankouh Pb/Zn mine encounter both drought stress and high levels of Pb. To better understand the role of drought and Pb in plant adaptation to Pb/Zn quarry tailings, we compared effects of drought stress (simulated by polyethylene glycol - PEG) and Pb, individually and in concert, to determine how these stressors affected two plant species: the metallicolous species Matthiola flavida (M) and the non-metallicolous congener, M. incana (NM). Plants were exposed to Pb (Pb(NO 3 ) 2 ) and three levels of PEG-6000 (0, -0.25, and -0.75 MPa) in a complete factorial design. Pb had non-significant effects on growth and oxidative stress but enhanced levels of osmoprotectants and phenol compounds in the M species M. flavida , whereas in M. incana the effect of Pb was non-significant on the same variables (except for anthocyanins and the osmoprotectants, proline and glycine betaine). Compared to M. incana , the M species M. flavida was tolerant of Pb, showing strongly reduced root-to-shoot translocation and enhanced Pb accumulation in the root (especially when under drought stress), which reduced toxic effects of Pb in the shoot. Tolerance of Pb by the M species M. flavida was aided by the accumulation of reducing sugars and phenolic compounds, as well as by greater catalase activity.

The Effect of Humidity on the Dissolution Kinetics and Tablet Properties of Immediate-Release Tablet Formulation Containing Lamotrigine.

This study aims to find the effects of high (75%) and low (30%) humidity conditions and its correlation with formulation composition on dissolution kinetics of lamotrigine (LMT) from prepared immediate-release tablets during one- and four-week periods. Two types of fillers microcrystalline cellulose (MCC) or anhydrous lactose (LAC), disintegrant sodium starch glycolate (NaSG, 0.5% or 4%), and lubricant magnesium stearate (MgST, 0.25% or 5%) were used. A three-factor two-stage complete factorial design (23) was used to assess the influence of the composition of the tested formulations. The tablets were produced by direct compression and characterized using a disintegration test, a resistance to crushing test, and dissolution tests (pH 1.2 and pH 6.8). Using Design Expert software, it was concluded that in addition to the effect of fillers on pH 6.8, NaSG has a significant impact after exposure to high and low humidity, as well as its interaction with LAC and MCC. In the dissolution medium pH 1.2, under conditions of high humidity, the content of MgST and NaSG and their interaction show a significant influence. The release rate of LMT was affected by humidity as well as type of excipients and their interactions.

Produced water treatment using microemulsion formulated with vegetable oil-based surfactant

The presence of produced water is common in oil production. In certain production stages, the volume of produced water exceeds that of oil. Pretreatment is necessary before the disposal or reinjection of produced water into wells because it is harmful to the environment owing to the high oil and grease contents (OGC), salinity, and other factors. This study proposes a produced water treatment using microemulsions (ME) with vegetable oil-based surfactants (S), with the aim of reducing two main factors, OGC and salinity. The decision to use a vegetable oil-based surfactant as an alternative to a petroleum-based surfactant was made to reduce the negative effects of the overall process on the environment. Coconut soap, the surfactant used in the formulated ME, was selected after testing a variety of vegetable oil-based surfactants. The other components used in the ME formulation were 2-butanol as a co-surfactant (C), pine oil as the oil phase, and saline water at 2 % NaCl as the water phase. The ME point used in the water treatment was defined by D-optimal mixture planning, composed of 85 % C/S, 2.5 % oil phase, and 12.5 % water phase, with a C/S ratio of 10. In addition, we used a complete factorial experimental design with combinations of three variables (time, temperature, and microemulsion percentage), and repetition of the central point to select the greatest reduction in OGC and salinity. According to the results, OGC reduction values ranged from 89.15 % to 95.43 %, with the real OGC values ranging from 16.98 mg·L−1 to 7.15 mg·L−1. These values are within the limits established by environmental agencies, CONAMA, US EPA, and the OSPAR Commission, for the disposal of produced water in the sea. In addition, salinity reduction varied from 38.02 % to 46.8 %, with real salinity decreasing from 36,223.53 mg·L−1 to 31,217.65 mg·L−1. Therefore, it can be said that using a vegetable oil-based and biodegradable surfactant in the microemulsion formulation for the treatment of produced water is as effective in the reduction of OGC and salinity as petroleum-based surfactants, which are more harmful to the environment.

Experimental and parametric studies on the effect of waste cooking oil methyl ester with diesel fuel in compression ignition engine

Diesel engine discharge characteristics are primarily influenced by fuel qualities, combustion chamber type, and injection settings. This study used combinations of biodiesel, waste cooking oil, and diesel fuel to do a parametric investigation on a diesel engine (DF80-WCOB20, DF70-WCOB30, DF60-WCOB40, and DF50-WCOB50). Using a complete factorial design L75 orthogonal array (O.A.), the experimental and parametric investigations were carried out. According to the experimental findings, DF80-WCOB20, DF70-WCOB30, DF60-WCOB40, and DF50-WCOB50 increase specific energy consumption while reducing engine efficiency, carbon monoxide emissions, and hydrocarbon discharges. At all engine loads, DF80-WCOB20′s brake thermal efficiency (BTE) was higher than that of DF70-WCOB30, DF60-WCOB40, and DF50-WCOB50 for respective compression ratios of 16.5, 17.5, and 18.5. Additionally, the BSFC for C.R. increases (16.5, 17.5, and 18.5) at all engine loads when waste cooking oil biodiesel is mixed with diesel fuel compared to diesel fuel. The findings indicate that while adding biodiesel made from used cooking oil to diesel fuel greatly reduces carbon monoxide and hydrocarbon emissions, it also results in higher nitrogen oxide emissions than diesel fuel.

Tillage and manure effects on runoff nitrogen and phosphorus losses from frozen soils.

In cold regions, nutrient losses from dairy agroecosystems are a longstanding and recurring problem, especially when manure is applied during winter over snow-covered frozen soils. This study evaluated two tillage (fall chisel tillage [CT] and no-tillage [NT]) and three manure-type management treatments (unmanured control, liquid manure [<5% solids], and solid manure [>20% solids]). The liquid and solid manure used in this study were from the same animal species (Bos taurus) and facility. The six management treatments were field tested in south-central Wisconsin during the winters (November-April) of 2017-2018 and 2018-2019 with a complete factorial design. Seasonal runoff losses were significantly lower from fall CT compared with NT during both seasons. Manure applications (both liquid and solid) on top of snow significantly increased most of the nutrients (NH4 + , dissolved reactive phosphorus, total Kjeldahl nitrogen, and total phosphorus) in runoff compared with unmanured control. Irrespective of tillage and multiple runoff events, solid manure was present on the surface for longer periods, potentially releasing nutrients each time it interacted with runoff. In contrast, liquid manure infiltrated the snowpack and was partly lost with snowmelt and infiltrated soil depending upon soil frost and surface conditions. Overall, results indicate that wintertime manure applications over snow-covered frozen soils pose a risk of nutrient loss irrespective of tillage and manure type, but in unavoidable situations, prioritizing tillage × manure type combination can help reduce losses.

Effect of extended mellowing on strength and swelling behaviour of a high sulfated soil

Troublesome events are related to the stabilisation of sulfate-rich soils with calcium-based materials. To overcome these inconveniences, research studies have been conducted applying modified and alternative treatments to soils containing low and high sulfate levels. This paper intends to assess the effects of mellowing period (MP) (2 and 4 days), Portland cement content (5%, 7% and 9%), density (15.75, 16.60 and 17.50 kN/m3) and curing time (14 and 28 days) on the performance of a clayey soil from the Paraguayan Chaco region containing high amounts of sulfates. A complete factorial design set was carried out to assess the unconfined compressive strength (UCS) and the one-dimensional free vertical swelling of compacted soil–cement–lime mixtures. The results showed a positive effect of the MP relative to the swelling of the stabilised soil. In addition, the curing period, the amount of cement and the dry unit weight were the most influential factors regarding the UCS. The stabilisation method addressed in this research – that is, extended mellowing combined with lime and Portland cement, seems to be of great importance for practical purposes on the stabilisation of soils containing high amounts of sulfates.

Optimization of parameters in laser welding of aluminum alloy 5052-H32 using beam oscillation technique for mechanical performance improvement

The beam oscillation is an innovative technique in laser welding resulting in important enhancement of the weld quality. This study assesses with numerical tools this improvement by investigating the effects of laser power, welding speed and amplitude on oscillated laser beam welding using a complete factorial design of three factors and two level followed by an analysis of variance (ANOVA) in aim to obtain repeatable high quality weld process for aluminum alloys. The result reveals that the amplitude has the most influential effect followed by the welding speed and the laser power. An increase of the amplitude oscillation tends weaken the mechanical resistance the weld by reducing the weld depth. An important interaction is found between the laser power and the welding in the statistical analysis and interpreted as the effect of specific point energy. An optimization using response surface method from the specific point energy and the amplitude figured out that the most resistant weld could be obtained by a specific point energy ranged between 25 J and 27 J combined with an amplitude of 0.75 mm. The results from validation test exhibit an increase of the welding speed by 66% for a tensile strength of 189 MPa denoting a gain in productivity for industrial application.

Effect of Yeast Bio-fertilizer on Lettuce Growth and Productivity

Background: Synthetic fertilizers and pesticides are widely used, with detrimental repercussions for soil microbial biodiversity and environmental contamination. The use of microorganisms as bio-fertilizers has been recommended as an alternative agricultural strategy. Due to their potential to safely boost plant development, yeasts can be used to make high-quality bio-fertilizers and biopesticides in a variety of ways. As a result, substantial yeast research could be promising and could provide an environmentally acceptable solution to the increasing agricultural output that would be necessary as the world’s population grows. Methods: The study was conducted to investigate the effect of different yeast concentrations on lettuce crop production and quality. The experiment consisted of four treatments (1%, 3%, 5% and 7% w/v yeast). The measurements included chlorophyll content, plant length (cm) and plant-wet weight for shoot and root (g). The design of the experiment was a complete factorial design with five replicates for each treatment. Three doses of each yeast solution, i.e. 1%-7% w/v, were added to soil after 7, 25 and 40 days from cultivation. The plants were harvested after 52 days. Result: In the current study, it was found that the highest chlorophyll content with a value of 44.6 was obtained at 3% w/v of yeast concentration followed by 1% w/v (39.7), 5% w/v (44.3) and 7% w/v (41), respectively. The average maximum length of plants after 52 days was 26.6 cm at 3% w/v and 26.13 cm at 5% (w/v) of yeast concentrations. The other treatments gave lower values, i.e. 24.4 cm, 22.2 cm and 19.1 cm for 1% w/v, 7% w/v and control, respectively,. The values have the same trend during the experiment time at the three stages (7, 25 and 40) days from cultivation. The optimum plant wet weight for shoot and root with 3% w/v yeast concentration were 212.2 and 33.9 g, respectively. At 5% w/v of yeast concentration, the wet weight for shoot and root were 200.1 g and 30.7 g followed by 7% w/v (196.2 g and 25.6 g) and 1% w/v (171.2 g and 26.4 g).