Axial Points Research Articles

Acoustic Trap Step for Single-Axis Acoustic Levitators

Acoustic manipulation is extensively employed due to its versatility and noncontact capability. Although significant developments have been made in this field, the dynamic process of the acoustic trap position in the manipulation of acoustically levitated objects has not been fully investigated, hindering the development of acoustic manipulation technology. Herein, we propose the gravity-acoustic trap morphology ($G$-ATM) method to elucidate the dynamic process in single-axis levitators. First, the acoustic trap step is defined to describe the dynamic process. Then, based on the $G$-ATM method, the study is carried out for single-axis levitators from the radial and axial points of view. In the radial direction, the stage concept is proposed to explain the impact of gravity, the impact of acoustic trap morphology is expressed by radial acoustic radiation force distribution, and transitional levitation states are observed and explained. In the axial direction, the impact of gravity is analyzed from the kinetic energy perspective, the impact of acoustic trap morphology is presented by multiple adjacent acoustic traps, and the principle of proximity followed by the motion of levitated objects is proposed. Finally, all analysis results are verified by simulations and experiments. The work will help to improve the rapidity and stability of acoustic manipulation and promote the development of acoustic manipulation technology.

On z-coherence of Schell-model sources carrying a prescribed astigmatic phase.

A simple expression for the correlations of beams radiated by Schell-model sources carrying a prescribed astigmatic phase (cross phase) in 3D space is derived. The z-coherence of such sources upon free-space propagation is investigated in detail. It is demonstrated that the z-coherence does not decrease to zero with an increasing separation of two axial points. Our results show that the initial cross phase, coherence, and correlation state of such sources affect the distribution of the z-coherence. Furthermore, the cross phase plays a role in maintaining z-coherence, which will be useful in applications where high z-coherence is required.

Gentle Driving of Piles (GDP) at a sandy site combining axial and torsional vibrations: Part I - installation tests

Gentle Driving of Piles (GDP) is a new technology for the vibratory installation of tubular (mono)piles. Its founding principle is that both efficient installation and low noise emission can be achieved by applying to the pile a combination of axial and torsional vibrations. Preliminary development and demonstration of the proposed technology are the main objectives of the GDP research programme. To this end, onshore medium-scale tests in sand have been performed on piles installed using both impact and vibratory driving methods (including GDP). After presenting the development of a purpose-built GDP driving device and the geotechnical characterisation of the site, this paper covers the execution of GDP installation tests. Focus is on the installation performance of GDP-driven piles, which is discussed with the aid of structural and ground monitoring data. The comparison between piling data associated with GDP and standard axial vibro-driving points out the potential of the proposed installation technology, particularly with regard to the beneficial effect of the torsional vibration component. The findings of this study encourage further development of the GDP method and its future extension to offshore full-scale conditions.

Bifurcation analysis of a predator–prey model involving age structure, intraspecific competition, Michaelis–Menten type harvesting, and memory effect

The complexity of the dynamical behaviors of interaction between prey and its predator is studied. The prey and predator relationship involves the age structure and intraspecific competition on predators and the nonlinear harvesting of prey following the Michaelis–Menten type term. Some biological validities are shown for the constructed model such as the existence and uniqueness as well as the non-negativity and boundedness of solutions. Three equilibrium points, namely the origin, axial, and interior points, are found including their global dynamics by employing the Lyapunov function along with the generalized Lassale invariant principle. The changes in dynamical behaviors driven by the harvesting and the memory effect are exhibited, including transcritical, saddle-node, backward, and Hopf bifurcations. The appearance of these interesting phenomena is strengthened by giving numerical simulations consisting of bifurcation diagrams, phase portraits, and their time series.

Calculation automation of “cemented doublet with a singlet” and “singlet with a cemented doublet” objectives

Subject of study. Automating the synthesis of “cemented doublet with a singlet” and “singlet with a cemented doublet” objectives with an entrance pupil on the first surface of the system is studied. The design of this type of system is complex owing to a large number of possible solutions. Moreover, when changing over from an infinitely thin system to a system with a finite thickness of elements, the image quality of axial points significantly deteriorates in most cases. This feature should be considered when developing an algorithm for lens design. Aim of study. The aim is to develop a method and algorithm for automatic synthesis of “cemented doublet with a singlet” and “singlet with a cemented doublet” objectives and a ranking system for designed objectives. Changes in the axial point image quality of the considered objectives with two or three different materials for possible acceleration of the synthesis process are also studied. Method. The initial design of objectives is carried out on the basis of the third-order aberrations theory. An automated exhaustive search is used to rank all possible combinations of lens materials. Main results. The methodology and algorithm of the automatic design of “cemented doublet with a singlet” and “singlet with a cemented doublet” objectives have been developed. A ranking system is provided to rank the designed objectives by the main criterion based on the axial point image size and by the preliminary criterion that determines the technological stability of the objective to the manufacturing errors of the optical elements. It is determined that the “singlet with a cemented doublet” objectives are generally preferable to “cemented doublet with a singlet” objectives according to the proposed criteria. Based on the calculation results, it is demonstrated that solutions with only two materials can have a slight decrease in the image quality of the axial point. Practical significance. Based on the developed algorithm, the program for the automatic design of two- and three-lens objectives is upgraded. The developed program will help optical engineers to significantly simplify and accelerate the process involved in designing two- and three-lens objectives with the required image quality characteristics.

Effect of the addition of bacterial cellulose on the texture and color properties of sausages obtained from mechanically separated meat from Nile tilapia (Oreochromis niloticus L.)

Bacterial cellulose has been considered a potential ingredient in food development. In this study it was used to replace fat in Nile tilapia (Oreochromis niloticus) mechanically separated meat sausages. Response surface methodology with complete Central Composite Rotatable Design (CCRD) 22 was used, including 4 axial points and 3 center points, with fat ranging from 0 to 8% and bacterial cellulose ranging from 0 to 13.66%. The variables BC and fat had no significant effect (p>0.05) on hardness, gumminess and color parameters c and h of sausages. BC had a significant effect (p<0.05) on cohesiveness, adhesiveness and luminosity, and tests 1 and 2 provided the best formulations.

Effect of calcium chloride and gelling agents on the physicochemical and sensory characteristics of sugar-free banana preserves.

Banana preserve is produced by mixing the puree of the fruit with sucrose and organic acids. However, concerns about body esthetics or health reasons have encouraged the search for low-calorie products. Therefore, the objective of this study was to evaluate the effect of calcium chloride (CaCl2), carrageenan gum, and low methoxyl pectin (LM-pectin) on the physicochemical and sensory characteristics of sugar-free banana preserves. By using a central composite rotational design (CCRD) of 2³ + 6 axial points + 4 central points, we obtained 18 formulations that were further tested. Lower CaCl2 concentrations (0.54% to 0.61%) resulted in preserves with lower pH and more vivid color. The increased concentration of LM-pectin (1.40% to 1.64%) resulted in formulations with a yellowish-red hue and with lower moisture, thus, reducing the flavor and purchase intention of the product. Higher concentrations of carrageenan gum (1.04% to 1.15%) decreased the perception of banana preserve aroma. Therefore, concentrations of CaCl2 ranging from 0.54% to 0.61%, carrageenan gum ranging from 0.74% to 0.89% and LM-pectin ranging from 1.40% to 1.64% resulted in sugar-free banana preserves with ideal sweetness and consistency and were, therefore, more acceptable.

A STUDY ON EQUILIBRIUM POINTS AND STABILITY OF THE ROBES R3BP WITH DENSITY VARIATION

The paper investigates equilibrium points and stability of an infinitesimal mass under the Robe restricted three-body problem with density variation. The equations of motion have been stated and the equilibrium points investigated. It is seen that axial equilibrium point at the centre and axial equilibrium points near the centre of the first primary were found. The axial points near the centre were further explored and it seen that five types of axial equilibrium points namely; minimal axial points, primary axial points of first kind, interior points, primary axial points of second kind and the terminal point, exists. These points are either located inside the first primary or on the points at which the circle bounding the first primary is coincident with the axis. Further a pair of non-collinear equilibrium points and circular equilibrium points which are points on the circle bounding the first primary, exists. The linear stability of these equilibrium points are investigated and it is seen that the axial points at the centre and those near the centre are conditionally stable analytically but our numerical explorations of the stability reveals that these points can be unstable and stable, a condition which depends on the mass parameter and the density variation of the fluid. The circular points are unstable due to double roots of the characteristic equation while the non-collinear equilibrium points are also unstable due to a positive root which induces instability at the non-collinear equilibrium points. For our numerical explorations of the equilibrium points and the stability outcomes, we in particular use the Submarine-Earth and Moon system and the general case for all mass ratios. The Robe’s problem has been useful in discussing the long time stability of the Earth’s core and for describing the motion of underwater vehicles under the Earth’s and Moon’s attraction.

Optimization of Wall Material of Freeze-Dried High-Bioactive Microcapsules with Yellow Onion Rejects Using Simplex Centroid Mixture Design Approach Based on Whey Protein Isolate, Pectin, and Sodium Caseinate as Incorporated Variables.

For the food sector, onion rejects are an appealing source of value-added byproducts. Bioactive compounds were recovered from yellow onion rejects using a pulse electric field process at 6000 v and 60 pulses. The onion extract was encapsulated with whey protein isolate (WPI), pectin (P), and sodium caseinate (SC) with a mass ratio of 1:5 (extract/wall material, w/w). A Simplex lattice with augmented axial points in the mixture design was applied for the optimization of wall material for the encapsulation of onion reject extract by freeze-drying (FD). The optimal wall materials were 47.6 g/100 g (SC), 10.0 g/100 g (P), and 42.4 g/100 g (WPI), with encapsulation yield (EY) of 85.1%, total phenolic content (TPC) of 48.7 mg gallic acid equivalent/g DW, total flavonoid content (TFC) of 92.0 mg quercetin equivalent/g DW, and DPPH capacity of 76.1%, respectively. The morphological properties of the optimal encapsulate demonstrated spherical particles with a rough surface. At optimal conditions, the minimum inhibitory concentration (MIC) of the extract (mean diameter of inhibition zone: 18.8 mm) was shown as antifungal activity against Aspergillus niger.

Application of Lactose-Free Whey Protein to Greek Yogurts: Potential Health Benefits and Impact on Rheological Aspects and Sensory Attributes.

The application of β-galactosidase in the fermentation of milk enables the acquirement of lower levels of lactose that are tolerated by lactose maldigesters and can reduce the nutritional consequences of avoiding dairy products. The present study evaluated the viability of the fortification of lactose-free prebiotic Greek yogurt formulas with whey protein concentrate (WPC). Two rotational central composite designs (RCCDs) were applied: one to perform the hydrolysis of the whey protein concentrate and another for the yogurt formulations (α = 2 with 2 central points and 4 axial points). Two β-galactosidase enzymes obtained from Kluyveromyces lactis were used. The content of lactose, glucose, galactose, and lactic acid were determined in the WPC, milk (pasteurized and powdered), and yogurts. The three best formulations regarding the attributes’ viscosity, syneresis, firmness, and elasticity were sensorially evaluated by using a nine-point hedonic scale. A microbiological analysis was performed after 48 h of yogurt production. The characterization of the products and the comparison of the results obtained were evaluated using the Student’s T test and the analysis of variance with Tukey’s test (p-values < 0.05). The application of a lactose-free WPC promoted viscosity, firmness, and elasticity. The syneresis was reduced, and whey increased the protein and calcium content. Lactose-free WPC can be used as a partial substitute for skimmed powdered milk in yogurts. The obtained results are encouraging with respect to the production of lactose-free Greek yogurts by the dairy industry.

Thermal study, process optimization, and water solubility improvement of a freeze-dried artemether nanosuspension for malaria treatment

This study aims to develop nanocrystals for improving the water solubility of artemether, an antimalarial drug substance. A compatibility study of the artemether and excipients was performed by differential scanning calorimetry and thermogravimetry to select an adequate stabilizer system. Soluplus® proved to be the most stable excipient evaluated. Artemether nanosuspension was prepared by miniaturized wet bead milling, using Soluplus® as a stabilizer. The process parameters were optimized firstly by a full 2³ factorial experimental design and then by response surface with axial points. The final composition of artemether nanosuspension provided a hydrodynamic diameter below 350 nm. The lyophilization process was developed by determining the glass transition, eutectic, and collapse temperature. Solid artemether nanocrystal presented an elegant cake appearance by visual inspection, and the hydrodynamic diameter practically did not change after water reconstitution. Differential scanning calorimetry and thermogravimetry revealed that the final artemether nanocrystal formulation and its components were thermally stable. The formulation presented an increase in water saturation solubility and pH 2.5–7.2 ranges, which was 3-fold higher in pH 7.2 than micronized artemether. These promising results present an excellent perspective for malarial treatment.

Tailoring the Optimized Fermentation Conditions of SCOBY-Based Membranes and Milk Kefir Grains to Promote Various Functional Properties.

Kombucha culture (named SCOBY-Symbiotic Culture of Bacteria and Yeasts) and milk kefir grains represent multiple consortia of wild microorganisms that include lactic acid bacteria, acetic acid bacteria and yeasts with valuable functional properties. Their fermentative potential provides a wide range of derivate metabiotics (prebiotics, probiotics, postbiotics and paraprobiotics) with valuable in vitro and in vivo benefits. This study targeted the evaluation of the functionality of a co-culture of SCOBY-based membranes and milk kefir grains, used as freeze-dried starter cultures, for the fermentation of a newly formulated medium based on black tea infusion, supplemented with bovine colostrum and sugar, in order to produce bioactive compounds with functional properties. The design and optimization of the biotechnological process were achieved by using the Plackett–Burman experimental design (six factorial points, three center points) and the response surface methodology and central composite design (three factorial points, six axial points and two center points in axial) tools. The statistical analysis and the mathematical modelling of the responses such as the pH, titratable acidity, antioxidant activity and antimicrobial activity (against Bacillus subtilis, Escherichia coli, Staphylococcus aureus and Aspergillus niger) were investigated. Further, the composition of organic acids, polyphenols and flavonoids of the fermented product obtained under the optimized fermentation conditions was also analyzed. The fermentation of the medium containing 6.27% (w/v) bovine colostrum powder, 1.64% (w/v) black tea, 7.5% (w/w) sugar, pH 6.7, with an inoculum based of 0.36% (w/v) milk kefir grains powder and 0.5% (w/v) SCOBY-based membrane (both as freeze-dried culture), at 30 °C, for 5 days, in an aerobic stationary system, revealed an antifungal activity between 80 and 100% against Aspergillus niger, an antibacterial activity of 8–22 mm against Escherichia coli and Bacillus spp. And a titratable acidity of 445 °Th. The chemical composition of the obtained product had a positive impact on the functional properties of the fermented products in terms of the antimicrobial and antioxidant properties.

Augmenting definitive screening designs: Going outside the box

Definitive screening designs (DSDs) have grown rapidly in popularity since their introduction by Jones and Nachtsheim (2011). Their appeal is that the second-order response surface (RS) model can be estimated in any subset of three factors, without having to perform a follow-up experiment. However, their usefulness as a one-step RS modeling strategy depends heavily on the sparsity of second-order effects and the dominance of first-order terms over pure quadratic terms. To address these limitations, we show how viewing a projection of the design region as spherical and augmenting the DSD with axial points in factors found to involve second-order effects remedies the deficiencies of a stand-alone DSD. We show that augmentation with a second design consisting of axial points is often the D s -optimal augmentation, as well as minimizing the average prediction variance. Supplemented by this strategy, DSDs are highly effective initial screening designs that support estimation of the second-order RS model in three or four factors.

Slope Rotatable Central Composite Designs of Second Type

Central composite design (CCD) is the most commonly used fractional factorial design used in the response surface model. Kim [1] proposed second order rotatable designs (SORD) of second type using CCD, in which the positions of axial points are indicated by two numbers\(\left(a_{1}, a_{2}\right)\). Kim and\(K_{0}\) [2] introduced second order slope rotatable designs (SOSRD) of second type using CCD, in which the positions of axial points are indicated by two numbers \(\left(a_{1}, a_{2}\right)\). In this paper, second order slope rotatable central composite designs of second type with\(2 \leq n_{3} \leq 4\) (where \(n_{\text {s }}\) denotes the number of replications of axial points) are suggested for \(2 \leq \mathrm{v} \leq 17\) (v-stands for number of factors). It is observe that the value of level \(\mathrm{a}_{2}\) (taking \(\mathrm{a}_{1}=1\) ) for the axial points in CCD required for slope rotatability for second type is appreciably larger than the value required for SORD of second type using CCD. And also noted that if we replicate axial points \(\left(n_{9}\right)\)in SOSRD of second type using \(\mathrm{CCD}\) then the value of \(\mathrm{a}_{2}\) (taking \(\mathrm{a}_{1}=1\) ) is approximately nearer to\(\mathrm{SORD}\) value \(\mathrm{a}_{2}\) of second type using CCD.

Analysis of the stability of oil-based drilling muds by electrical stability measurements as a function of oil-water ratio, weighting material and lubricant concentrations

Oil-based muds (OBM) used in drilling processes are complex fluids formed by a water-in-oil emulsion stabilized by emulsifiers. Measurements of the electrical stability (ES) are considered directly indicators of mud stability, together with yield point (YP), and fluid loss (FL). In this work, it was studied the effect of oil-water ratio (OWR) in the mud stability using the ES, YP and FL data. To analyze those individuals and paired effects, it was applied a Central Composite Rotational Design (CCRD) planning with three replicates at the central point plus eight and six factorial and axial points. Results showed that all studied factors presented a high influence on the ES results. Additional measurements of rheological properties and fluid loss were carried out to verify and analyze the impact of the composition on the main drilling mud properties. Statistical analysis was also performed to clarify the role of the different factors investigated in this research. The authors observed that several drilling mud compositions are not suitable for the oilfield application, and, by an optimization procedure, an optimal formulation has been proposed.

Wave Equation Numerical Simulation and RTM With Mixed Staggered-Grid Finite-Difference Schemes

For the conventional staggered-grid finite-difference scheme (C-SFD), although the spatial finite-difference (FD) operator can reach 2Mth-order accuracy, the FD discrete wave equation is the only second-order accuracy, leading to low modeling accuracy and poor stability. We proposed a new mixed staggered-grid finite-difference scheme (M-SFD) by constructing the spatial FD operator using axial and off-axial grid points jointly to approximate the first-order spatial partial derivative. This scheme is suitable for modeling the stress–velocity acoustic and elastic wave equation. Then, based on the time–space domain dispersion relation and the Taylor series expansion, we derived the analytical expression of the FD coefficients. Theoretically, the FD discrete acoustic wave equation and P- or S-wave in the FD discrete elastic wave equation given by M-SFD can reach the arbitrary even-order accuracy. For acoustic wave modeling, with almost identical computational costs, M-SFD can achieve higher modeling accuracy than C-SFD. Moreover, with a larger time step used in M-SFD than that used in C-SFD, M-SFD can achieve higher computational efficiency and reach higher modeling accuracy. For elastic wave simulation, compared to C-SFD, M-SFD can obtain higher modeling accuracy with almost the same computational efficiency when the FD coefficients are calculated based on the S-wave time–space domain dispersion relation. Solving the split elastic wave equation with M-SFD can further improve the modeling accuracy but will decrease the efficiency and increase the memory usage as well. Stability analysis shows that M-SFD has better stability than C-SFD for both acoustic and elastic wave simulations. Applying M-SFD to reverse time migration (RTM), the imaging artifacts caused by the numerical dispersion are effectively eliminated, which improves the imaging accuracy and resolution of deep formation.

Design and Optimization of Floating Microspheres Using Abelmoschus esculentus Natural Polymer

The main objective of the present research study was to fabricate Vildagliptin floating microspheres by ionotropic gelation using natural polymer, Abelmoschus esculentus obtained from the fruits of Abelmoschus esculentus in combination with sodium alginate. Microspheres were prepared and optimized using central composite rotatable design model using design expert software version 12 .The study is focussed on the interaction effects of the three independent variables, natural polymer concentration, sodium alginate concentration and crosslinker concentration, optimization of formulations response surface methodology was used . drug –excipient compatibility studies were carried out by infrared spectroscopic studies. Infrared spectroscopic studies clearly shown that drug and excipients were compatible. Totally 15 formulations were generated taking 8 factorial points, 6 axial points and 1 centre point. Response surface methodology was used to optimize the formulations. To investigate the responses %cumulative drug release, floating time and floating lag time Response surface methodology was used Polynomial equations and model plots of 3 dimensional model surface plots were generated. Vildagliptin optimized microspheres were formulated and a second order, model quadratic model was used to study influence of formulation factors on response variables. Experimental data of Statistical analysis exhibited good coefficient of regression for cumulative in vitro drug release Regression F –ratios for the experimental variables were significant. The experimental values and predicted values are agreed. All fifteen formulations exhibited % yield of 94.35-99.99%, particle size of 124-441µm, %swelling index 64.52-89.65%, floating time of 10.16 to 13.16 and floating lag time of 30.31 to 46.98 sec. F4 formulation is optimized based on cumulative % in-vitro drug release at 2nd hour, 12th hour, floating lag time and floating time values. Predicted and observed results are in agreement 95% confidence intervals. Based on investigation, RSM is the good tool for optimization of formulations.

Experimental investigations on aviation kerosene Multi-jets in high temperature and low pressure air crossflow

There are the key factors affecting the combustion performance of the burner, including the jet trajectory, fragmentation and evaporation process of fuel jet in air crossflow and the uniform characteristics of fuel-gas mixing. In our experimental investigation, we studied the effects of liquid/air momentum flux ratio, the number of radial and axial injection points on jet trajectory, penetration depth and Sauter mean diameter (SMD) distribution of aviation kerosene injected into high temperature and low pressure air crossflow. Specifically, the pressure of air crossflow was set to 0.06–0.09Mpa, the speed 0.1 Ma, and the temperature 500 K. The jet trajectories of aviation kerosene were captured using a triggered image sensor (CCD) camera; the SMD of the aviation kerosene along the flow direction was measured using a Malvern laser particle sizer. The main observation results are: (1) The liquid/air momentum flux ratio is still the main factor affecting the penetration depth of liquid jet, fitting the dimensionless formula of jet trajectories of aviation kerosene injected into high temperature and low pressure lateral airflow. The fitting formula of single injection point and multiple injection points is y/d=0.4357q0.8384x/d0.4797 and y/d=0.513q0.8869x/d0.3661 respectively. (2) When the air crossflow pressure goes down, it will reduce the aerodynamic Weber number and increase the penetration depth, while it will reduce the Reynolds number of jet liquid and increase the average droplet size. For every 0.01Mpa decrease in air crossflow pressure, the aviation kerosene particle size SMD increases by 5–20 µm. (3) When the number of radial jet points goes up, it will enhance the interaction between CVP (Counter Rotating Vortex Pairs) and complex vortex system between multiple jets, which leads to rising growth rate of jet liquid column surface wave and the premature break-up, reducing the penetration depth by 15–25 mm; Compared with the single injection point, the influence of liquid/air momentum flux ratio on the jet trajectory and penetration depth of the multi-injection point becomes smaller, and the difference is more obvious under the condition of high liquid/air momentum flux ratio.

Study on Rotating Stall of Multistage Compressor Using Wavelets

Rotating stall in the high speed compressor can lead to violent disruption of flow, damage to the blade structures and, eventually, engine shutdown. To investigate the mechanism of stall inception and stall propagation in multi-stage compressor, the onset and transient behavior of rotating stall in a transonic 2-stage compressor are simulated based on the in-house software ASPAC. Many sampling points are placed to monitor the flow variation. The analysis results of circumferential sampling points indicate that, the spectral characteristics of circumferential sampling points in steady state and unstable state are similar, the pressure pulsation is similar, but there exist phase difference. In the transition state, the main frequency is similar and the secondary frequency is slightly different, the 17th blade channel at the blade top of rotor 2 produces a disturbance with lower frequency and higher amplitude before other channels, which triggers the stall disturbance. The analysis results of axial sampling points show that the blade row interference frequency exists in the whole flow change process, and the disturbance of adjacent blade rows is dominant. The stall disturbance starts with rotor 2. This initial disturbance soon spreads to its adjacent stator 1 and stator 2. Rotor 1 is finally affected and enters into unstable state at about the 12th revolution.

Enzymatic Synthesis of Fatty Acid Isoamyl Monoesters from Soybean Oil Deodorizer Distillate: A Renewable and Ecofriendly Base Stock for Lubricant Industries.

In this study, soybean oil deodorizer distillate (SODD), a mixture of free fatty acids and acylglycerides, and isoamyl alcohol were evaluated as substrates in the synthesis of fatty acid isoamyl monoesters catalyzed by Eversa (a liquid formulation of Thermomyces lanuginosus lipase). SODD and the products were characterized by the chemical and physical properties of lubricant base stocks. The optimal conditions to produce isoamyl fatty acid esters were determined by response surface methodology (RSM) using rotational central composite design (RCCD, 23 factorial + 6 axial points + 5 replications at the central point); they were 1 mol of fatty acids (based on the SODD saponifiable index) to 2.5 mol isoamyl alcohol, 45 °C, and 6 wt.% enzymes (enzyme mass/SODD mass). The effect of the water content of the reactional medium was also studied, with two conditions of molecular sieve ratio (molecular sieve mass/SODD mass) selected as 39 wt.% (almost anhydrous reaction medium) and 9 wt.%. Ester yields of around 50 wt.% and 70 wt.% were reached after 50 h reaction, respectively. The reaction products containing 43.7 wt.% and 55.2 wt.% FAIE exhibited viscosity indices of 175 and 163.8, pour points of −6 °C and −9 °C, flash points of 178 and 104 °C, and low oxidative stability, respectively. Their properties (mainly very high viscosity indices) make them suitable to be used as base stocks in lubricant formulation industries.