Axial Points Research Articles

Multielemental analysis of Antarctic soils using calibration free laser-induced breakdown spectroscopy

Laser-induced breakdown spectroscopy (LIBS) is a quick technique that allows the analysis of all types of samples without destroying them and with much reduced sample treatment. One of its many applications is the study of geological samples such as soils. Because of the complexity of the matrix, it is very difficult to find or manufacture standards for these types of samples. Therefore, a good alternative is to make use of a methodology, called Calibration Free (CF), where instead of using standards, the physical parameters of the plasma created by the interaction of the laser with the sample are studied and related to the elements and species that compose it. This methodology is followed to perform a multielemental quantitative analysis of soil samples from Antarctica. Two studies were made, differing in the optimization of the instrumental parameters in order to obtain the best possible spectra in the chosen spectral lines. In both cases, the signal to noise ratio (SNR) was used to evaluate the quality of the spectra, but in the second study a full factorial design 23 with center and axial points was developed to get better results. The choice of spectral lines was based on a series of criteria, being stricter in the second study. The samples were mainly composed of the following oxides: SiO2, Al2O3, Fe2O3, CaO, MgO, Na2O, TiO and K2O. In the second study, it was also possible to determine the species present in lower concentrations: Mn, Cr, V, Sr, Zr, BA and Li. The results were compared with those provided by ICP-OES analysis, obtaining close values for most oxides, especially in the second study. For minority elements, the CF-LIBS and the ICP-OES results were within the same order of magnitude in all cases except the Cr case. These results show that CF-LIBS can be very useful in the characterization of complex samples from remote regions, such as Antarctic soils.

Dynamics of a fractional epidemiological model with disease infection in both the populations

In order to depict a situation of possible spread of infection from prey to predator, a fractional-order model is developed and its dynamics is surveyed in terms of boundedness, uniqueness, and existence of the solutions. We introduce several threshold parameters to analyze various points of equilibrium of the projected model, and in terms of these threshold parameters, we have derived some conditions for the stability of these equilibrium points. Global stability of axial, predator-extinct, and disease-free equilibrium points are investigated. Novelty of this model is that fractional derivative is incorporated in a system where susceptible predators get the infection from preys while predating as well as from infected predators and both infected preys and predators do not reproduce. The occurrences of transcritical bifurcation for the proposed model are investigated. By finding the basic reproduction number, we have investigated whether the disease will become prevalent in the environment. We have shown that the predation of more number of diseased preys allows us to eliminate the disease from the environment, otherwise the disease would have remained endemic within the prey population. We notice that the fractional-order derivative has a balancing impact and it assists in administering the co-existence among susceptible prey, infected prey, susceptible predator, and infected predator populations. Numerical computations are conducted to strengthen the theoretical findings.

D-Optimal Designs for Second-Order Response Surface Models with Qualitative Factors

Central composite design (CCD) is widely applied in many fields to construct a second-order response surface model with quantitative factors to help to increase the precision of the estimated model. When an experiment also includes qualitative factors, the effects between the quantitative and qualitative factors should be taken into consideration. In the present paper, D-optimal designs are investigated for models where the qualitative factors interact with, respectively, the linear effects, or the linear effects and 2-factor interactions or quadratic effects of the quantitative factors. It is shown that, at each qualitative level, the corresponding D-optimal design also consists of three portions as CCD, i.e. the cube design, the axial design and center points, but with different weights. An example about a chemical study is used to demonstrate how the D-optimal design obtained here may help to design an experiment with both quantitative and qualitative factors more efficiently.

Second Order Rotatable Designs of Second Type Using Central Composite Designs

Kim [1] introduced rotatable central composite designs of second type with two replications of axial points for 2≤v≤8 (v: number of factors). In this paper we have extended the work of Kim [1] for second order rotatable designs of second type using central composite designs for 9≤v≤17.

Formulation of Tablets in Capsule system: Statistical optimization for chronotherapeutic drug delivery of propranolol hydrochloride

Chronic diseases like asthma, hypertension and rheumatoid arthritis requires prompt release of drug as per the disease condition. Conversely, extended release systems can only maintains the drug concentration with in therapeutic range for prolonged period of time, which not be the primary requisite for the foresaid diseases. The early morning surge of blood pressure was reported to be associated with a high risk of hemorrhagic stroke and cardiac death. This can be overcomeby programmed lag time, through designing of chronotherapeutic drug delivery systems (CDDS), that can be beneficial for the delivery of Propranolol hydrochloride at required time. The goal of the present study is to explore and optimize various parameters in designing Tablets in Capsule system (TCS) using response surface methodology to release the medication as per the chronological conditions of the disease. Initially, coating of capsule body was optimized in order to maintain its integrity for more than 12 h. Subsequently, erodible tablet formulation was optimized via a face-centered central composite design. Concentration of guar gum (X1) and total erodible tablet weight (X2) were selected as independent variables and these were studied at five different levels (±1 - factorial points, ± 1.141- axial points and center point −0) to optimize the cumulative drug release at the end of 5 h [CDR (6 h)- Y1] and time taken to release 98% of drug [T 98% - Y2], using Design Expert 11. On basis of Global desirability function (D) criteria, formulation with guar gum concentration of 35.589 mg and total tablet weight of 150 mg can accomplish the prerequisites of optimum formulation and the use of such combination shows, 6.946% of CDR at the end of 5 h and time taken to release 98% of Propranolol hydrochloride was found to be 12 h. Chronotherapeutic system requires of at least 5–6 h of lag time and followed by the complete drug release within 12 h, that matches with the optimized formulation. However, this work should extend to in vivo pharmacokinetic studies to conform the in vitro in vivo correlation.

Scaled Prediction Variances of Equiradial Design under Changing Design Sizes, Axial Distances and Center Runs

The aim of every design choice is to minimize the prediction error, especially at every location of the design space, thus, it is important to measure the error at all locations in the design space ranging from the design center (origin) to the perimeter (distance from the origin). The measure of the errors varies from one design type to another and considerably the distance from the design center. Since this measure is affected by design sizes, it is ideal to scale the variance for the purpose of model comparison. Therefore, we have employed the Scaled Prediction Variance and D – optimality criterion to check the behavior of equiradial designs and compare them under varying axial distances, design sizes and center points. The following similarities were observed: (i) increasing the design radius (axial distance) of an equiradial design changes the maximum determinant of the information matrix by five percent of the new axial distance (5% of 1.414 = 0.07) see Table 3. (ii) increasing the nc center runs pushes the maximum SPV(x) to the furthest distance from the design center (0 0) (iii) changing the design radius changes the location in the design region with maximum SPV(x) by a multiple of the change and (iv) changing the design radius also does not change the maximum SPV(x) at different radial points and center runs . Based on the findings of this research, we therefore recommend consideration of equiradial designs with only two center runs in order to maximize the determinant of the information matrix and minimize the scaled prediction variances.

Competitive spirit as a form of behavioral addiction: the case study of Michael Jordan

Abstract When studying biographical narratives constituting “The Michael Jordan Myth,” certain patterns emerge. For example, it is possible to identify mythemes corresponding with Campbell’s concept of the hero’s journey monomyth. This study focuses on a particular pattern, which is a progression of addiction with its phases, axial points, and list of symptoms. One of the most frequently used epithets in regard to the hero of this particular myth is “competitive.” While this is a quality of numerous outstanding athletes, in Jordan’s case competitiveness appears as a dominant quality and a driving force throughout his entire career. The premise of my study is the assumption that Jordan’s competitive spirit is a symptom of behavioral addiction and winning/defeating rivals is the behavior of an addict. The goal of the study is to use Jordan’s biographies and, based on Jellinek’s model of addiction progression, to verify whether Jordan’s accomplishments on and off the court can be viewed as symptoms of unclassified behavioral addiction.

Recovery of Bioactive Compounds from Pomegranate (Punica granatum L.) Peel Using Pressurized Liquid Extraction.

Pressurized liquid extraction (PLE) is a clean and environmentally friendly alternative for the recovery of bioactive compounds from fruit by-products. Herein we focused on PLE for the extraction of bioactive compounds from pomegranate peel using a combination of pressurized water and ethanol. The main aim was to determine the optimal PLE conditions, i.e., ethanol percentage and process temperature, to obtain a pomegranate peel extract (PPE) with maximum total phenolic content (TPC), punicalagin content, and antimicrobial activity (AMA). The experimental design was conducted using a central composite design with axial points. Response surface methodology was applied to optimize the response variables using the desirability function. Multiple response optimization indicated a process temperature of 200 °C and ethanol of 77% as optimal conditions. The TPC and the punicalagin content of PPE-PLE obtained under optimal conditions were 164.3 ± 10.7 mg GAE/g DW and 17 ± 3.6 mg/g DW, respectively. Our findings support the efficacy of PLE on TPC recovery but not in punicalagin recovery. The AMA against S. aureus was 14 mm. The efficacy of PPE-PLE in food applications must continue to be studied in order to achieve adequate information on its potential for developing new food additives.

Production and Optimization of Ultrafine Fiber from Yam Starch by Electrospinning Method Using Multivariate Analysis

AbstractThe aim of this study is to produce ultrafine fibers based on native yam starch as a polymeric material using the electrospinning technique. For this purpose, a 2³ multivariate design is used, with central and axial points in order to optimize the electrospinning operating conditions (source voltage, distance between the needle and the collector, and flow of the polymeric solution). The morphology and diameter of the ultrafine fibers are evaluated by scanning electron microscopy. The investigated responses are the average diameter of the fibers, the standard deviation of the average diameter, and the number of beads. The optimum condition for the production of ultrafine fibers is: voltage of 20 kV, distance between the needle and the collector of 20.5 cm, and flow of 1 mL h−1. With these conditions, it is possible to form fibers with an average diameter of 134.1 ± 16.71 nm, with homogeneous morphology, and without beads.

Preliminary estimate of instrumental polarization effects in the LST-3 Large Solar Telescope

This article presents a polarization calculation for the LST-3 large solar telescope. It describes the interaction of the telescope mirrors and includes a calculation of the transmittance of the telescope’s optical system for incident radiation with various polarization states. It estimates the instrumental polarization, cross-talk, and depolarization at Gregorian focus F2 and after tilted mirror M4 of the telescope. The estimate is made using modeling of an aluminum coating on the mirrors for axial and peripheral image points at reference wavelengths in the 400–2000 nm region. The mean Mueller matrices are found at Gregorian focus F2 and after tilted mirror M4. The polarization distortions at the Gregorian focus are insignificant, but they are substantial after tilted flat mirror M4.

Unraveling the combined actions of a Holling type III predator–prey model incorporating Allee response and memory effects

In this article, we have studied a memory dependent prey–predator model with logistic type prey growth subject to the Allee effect and Holling type-III functional response. To include the memory effect, we have used here a fractional order system. The model contains at most four equilibrium points among which one is trivial, two are axial, and the last one is interior. Here we have studied behavior of these four equilibrium points using eigen analysis method. Our investigation shows that the trivial equilibrium point is stable for strong Allee effect, and unstable for weak Allee effect. Between the two axial equilibrium points, one is stable under certain condition but the other is always unstable. This unstable equilibrium point exists only for strong Allee case. The interior equilibrium point arises when the axial equilibrium point is unstable. Stability condition of this interior equilibrium point depends on the parametric relationship. The schematic diagram divides the a-p plane into five sub-regions in both the cases of memory dependent and memory less system. The number and nature of the equilibrium points in different sub-regions are different. Finally, we have drawn the bifurcation diagrams considering all the equilibrium points in different sub-regions and the results are concluded at the end.

Application of response surface methodology (RSM) in statistical optimization and pharmaceutical characterization of a patient compliance effervescent tablet formulation of an antiepileptic drug levetiracetam

BackgroundThe main objective of the present study was to develop and optimize an effervescent tablet of levetiracetam, an antiepileptic drug, using central composite design with response surface methodology (RSM).The present investigation helps to overcome the problem associated with levetiracetam tablets and liquid dosage forms with children and elderly people like bad taste and swallowing difficulties. It also facilitates as an alternative manufacturing process for advanced patented technology like 3D printing process employed in SPRITAM® tablet.Levetiracetam effervescent tablets were prepared by dry granulation (roll compaction) method using water-soluble excipients and optimized by central composite rotatable design (CCRD) using two variables (citric acid and effersoda) at two levels (high and low). Overall, fourteen formulation trials were generated through statistical software Minitab 17.3.0 placing 6 center points, 4 cube points, and 4 axial points. All formulations were subjected to compression using single punch machine.ResultsQuality attributes of compressed tablets were evaluated using various compendial and non-compendial tests. RSM was used to observe the responses like effervescent time, hardness, and friability of the prepared tablet batches for different levels of all the variables. Polynomial equations were developed, and model plots (contour plot and 3-dimensional model surface plots) were generated to study the impact of acid-base couple on the responses. Finally, the optimized formulation was selected on the basis of desired effervescent time, hardness, friability, percent drug release, and drug content. From the studied RSM design, it was observed that small changes in the independent variables (citric acid and effersoda) correlate with shifts in the dependent variables, i.e., the desired responses. The study reveals that all the independent variables (citric acid and effersoda) and dependent variables (effervescent time, hardness, and friability) have a good correlation as indicated by good linear regression coefficient of 0.9808, 0.9939, and 0.9892 for effervescent time, hardness, and friability respectively.ConclusionLevetiracetam effervescent tablets are satisfactorily prepared by dry granulation (roll compaction) approach. All desired critical quality attributes were found to be satisfactory. The applicability of RSM with desirability function in optimizing the levetiracetam formulation has made it possible to identify the impact of various independent variables and explore their effect on required responses.

Experimental investigation and regression modelling to improve machinability in CNC turning of CALMAX® tool steel rods

This paper studies the effect of cutting conditions (spindle speed - rpm; feed rate - mm/rev and depth of cut - mm) on main cutting force and surface roughness during CNC turning of the commercial tool steel CALMAX® by Uddeholm (Sweden). Experiments have been designed using the Central composite design (CCD) approach. The experimental design involved twenty base runs with eight cube points, four center points in the cube, six axial points and two center points in axial direction. Statistical analysis to examine the effect of cutting conditions on the responses of main cutting force and surface roughness included ANOVA under the scope of generating a full quadratic model for predicting the responses. Finally, a feed-forward back-propagation neural network was applied to predict the responses of cutting force and surface roughness. It was found that regression models corresponding to the responses as well as the neural network developed can efficiently explain much of the variation in terms of main cutting force and surface roughness and thereby they may be implemented to practical applications either for predicting actual machinability parameter values or for setting up objective functions to be evaluated by intelligent algorithms for process optimization.

Evaluation of nopol production obtained from turpentine oil over Sn/MCM-41 synthesized by wetness impregnation using the Central Composite Design

A face-centered Central Composite Design (CCD) was used for nopol synthesis from turpentine oil over Sn/MCM-41 catalyst synthesized with sodium silicate as silicon source and incorporating Sn by wetness impregnation using SnCl2.2H2O as metal source. The catalyst was characterized by XRD, NH3-TPD and UV–vis-DRS. The catalyst was used four times without an apparent loss of catalytic activity and with no leaching of Sn. The CCD was constructed from 24 factorial points, eight axial points and seven central points, with time, paraformaldehyde to β-pinene molar ratio, catalyst concentration and solvent to β-pinene ratio as factors. Three response variables were selected (β-pinene conversion, nopol selectivity and nopol yield), and second order models were obtained taking into account all possible effects and identifying the non statistically significant effects. The optimal values found by response surface methodology were 71 %, 99 % and 61 % for conversion, selectivity and yield, respectively. The reactions were carried out under the established optimal conditions and the error varied between 2.14 and 2.63 %. Finally, the assumptions of independence, normality and homoscedasticity for each of the models were satisfactorily validated.

Optimization of microencapsulation of selenium with gum Arabian/Persian mixtures by solvent evaporation method using response surface methodology (RSM): soybean oil fortification and oxidation indices

Optimization of microencapsulation of sodium selenite 100–900 mg with a combination of Arabian gum 25–29% and Persian gum 5–1% per 20 ml mix spray solution by a solvent evaporation method using response surface methodology with central composite design (α = 2 with 6 central points and 2 repetition in axial and factorial points) were investigated. This study aimed to production of microencapsulated selenium with the highest encapsulation efficiency (EE) and the smallest particle-size for increasing soybean-oil shelf life against oxidation. The optimal-formula-1 (135 mg Na-selenite, Arabian to Persian gum ratio 9) with an actual EE of 77.35% and particle-size of 48.20 μm and the optimal-formula-2 (109 mg Na-selenite, Arabian to Persian gum ratio 14) with an actual EE of 93.74% and particle-size of 45.20 μm produced. Consequently, the un-microencapsulated sodium-selenite (8.6 ppm of sodium-selenite, equivalent to 3.93 ppm pure selenium, regarding recommended daily intake of 55 μg for Selenium and 14 g for oil), the two selected optimal formulas (containing 8.6 ppm sodium-selenite, i.e., 3.92 ppm pure selenium), the BHA (200 ppm), were added to refined antioxidant-free soybean oil (as a control treatment) and then were placed at the 55 °C for (0, 23, 46 days) equaled to 20 °C (0, 180, 360 days) by a shelf-life accelerator program. The oxidation indices including, total acid number, peroxide value, thiobarbituric acid value, para-Anisidine value, and Totox value as well as, antioxidant activity in soybean-oil over a 1-year storage-time at 20 °C showed the order of the proposed treatments were included 482 ppm optimal-formula-2 ≥ 391 ppm optimal-formula-1 ≥ 200 ppm BHA > 8.6 ppm un-microencapsulated Na-selenite > blank treatments. Optimization of selenium microencapsulation process using Arabian-Persian gum profile and different amounts of sodium slenite by RSM (Part 1) and Assessment of the oxidation indices in refined antioxidant-free soybean oil containing microencapsulated optimal formulas in 365-day storage time at 20 °C (Part 2)

Axial contact points method for improving end-milling productivity

The article analyzes results of a study on the effects of cutting data on cutting forces when end milling titanium alloys. A solid carbide mill was used. Stability of the milling process is ensured by optimal values of axial depth of cut using the axial contact points (ACP) method. The radial depth of cut and feed were varied to achieve a required level of milling productivity. Cutting forces and vibrations were measured when milling. Vibrations were measured in the frequency and time domains. Possibilities of reducing cutting forces without decreasing the productivity level by choosing optimal values ​​of cutting parameters were studied. The practical significance of the research results for planning milling processes in real production conditions was demonstrated. Ways to improve end milling productivity for titanium alloys by reducing loads on the technological system were identified. Avenues for further research on high-productivity end milling of titanium alloys were proposed.

The Local Bifurcation of an Eco-Epidemiological Model in the Presence of Stage- Structured with Refuge

In this paper, we establish the conditions of the occurrence of the local bifurcations, such as saddle node, transcritical and pitchfork, of all equilibrium points of an eco-epidemiological model consisting of a prey-predator model with SI (susceptible-infected) epidemic diseases in prey population only and a refuge-stage structure in the predators. It is observed that there is a transcritical bifurcation near the axial and free predator equilibrium points, near disease-free equilibrium point is a saddle-node bifurcation and near positive (coexistence) equilibrium point is a saddle-node bifurcation, a transcritical bifurcation and a pitchfork bifurcation. Further investigations for Hopf bifurcation near coexistence equilibrium point are carried out. Finally, numerical simulations are used to illustrate the occurrence of the local bifurcations of this model.

Repeatability of Zone Averages Compared to Single-Point Measurements of Maximal Curvature in Keratoconus

To evaluate the repeatability of curvature zone averages centered on the point of maximum curvature (Kmax) compared to that of the single-point Kmax. Comparative reliability analysis. Setting: American University of Beirut Medical Center, Beirut, Lebanon. Sixty-five eyes of 65 adult keratoconus patients. Patients with other ocular disease, history of ocular surgery or trauma, and contact lens wear within 2weeks of image acquisition were excluded. Eyes were evaluated with 3 consecutive scans using the Galilei dual Scheimpflug-Placido system. Repeatability of axial and instantaneous Kmax single points, and zone averages with radii of 0.1-2.0mm, centered on them. Repeatability was assessed by within-subject standard deviations, repeatability limits (r), and intraclass correlation coefficients. Axial curvature zone averaging yielded clinically acceptable repeatability only in eyes with Kmax ≤50 diopters (D), for radii of 1.5mm and 2.0mm (r= 0.87 D and r= 0.76, respectively, vs r= 0.91 for the single-point axial Kmax). Compared to instantaneous Kmax, clinically acceptable repeatability was achieved with instantaneous zone averages of at least 1.5mm radius in eyes with Kmax ≤50 D (r= 0.99 D and r= 0.70 D, respectively) and 2.0mm radius in eyes with Kmax >50 D (r= 2.28 D and r= 0.87 D, respectively). For all eyes, the repeatability limit of the location of Kmax was 0.82mm and 0.80mm for axial and instantaneous curvature, respectively. Instantaneous curvature zone averages centered on Kmax yielded a greater improvement in repeatability than axial zone averages and reached clinical adequacy with radii of at least 1.5mm, for eyes with Kmax ≤50 D, and with a 2.0mm radius for eyes with Kmax >50 D.

Evaluation of time, temperature and concentration of solvent, in the extraction of bioactive compounds from carrot (daucus carota)

The objective of this work was to analyze the content of bioactive compounds extracted from the carrot, through an experimental design of 3 factors, 3 levels and two axial points, including extraction time (17-37-57min), temperature (30-50-70ºC) and ethanol concentration (50-65-80%). The result was expressed as a percentage. Based on the results, it can be said that time did not significantly influence the extraction of antioxidant compounds (p> 0.001), and that the temperature is directly proportional to the yield. Regarding phenolic compounds, only temperature was significant, and for flavonols, only time and proportion. The use of ethanol as a solvent showed good results when compared to the commonly used solvents, in addition to having the quality of being economically viable and food grade. Another important factor was the pre-treatment of the sample, which allowed good yield values ​​when compared to the literature.

Optimization of oxalate-free starch production from Taro flour by oxalate oxidase assisted process

Taro (Colocasia esculenta) starch is known to possess unique physical and functional properties such as low amylose content, A-crystalline form, small granules, higher swelling power, etc. Due to the presence of significant amount of calcium oxalate crystals, the food industry is reluctant to explore this unique and cheap starch source for various food applications. Traditional processes utilizing various physical and chemical methods to remove oxalate content of starch inevitably change its physical and functional properties. However, using oxalate oxidase can effectively remove oxalates without altering the unique properties of starch. Hence, an attempt was made to optimize oxalate oxidase assisted starch extraction process from taro flour using response surface methodology. A central composite design comprising 20 experimental trials with 10 cube points augmented with six axial points and four replicates at the center point was applied. A mathematical model was developed to show the effect of taro flour concentration, enzyme load and incubation time on the oxalate removal. Validity of the model was experimentally verified and found that 98.3% of total oxalates can be removed under optimal conditions. This is the first report of optimization of the production of starch from taro flour using microbial oxalate oxidase.