Best-fit Equation Research Articles

RETRACTED ARTICLE: Application of artificial neural networks for analytical modeling of Charpy impact energy of functionally graded steels

In the present study, the Charpy impact energy of ferritic and austenitic functionally graded steel produced by electroslag remelting has been modeled in crack divider configuration. To produce functionally graded steels, two slices of plain carbon steel and austenitic stainless steels were spot welded and used as electroslag remelting electrode. Functionally graded steel containing graded layers of ferrite and austenite may be fabricated via diffusion of alloying elements during remelting stage. Vickers microhardness profile of the specimen has been obtained experimentally and modeled with artificial neural networks. To build the model for graded ferritic and austenitic steels, training, testing and validation using, respectively, 174 and 120 experimental data were conducted. According to the input parameters, in the neural networks model, the Vickers microhardness of each layer was predicted. A good fit equation that correlates the Vickers microhardness of each layer to its corresponding chemical composition was achieved by the optimized network for both ferritic and austenitic graded steels. Afterward, the Vickers microhardness of each layer in functionally graded steels was related to the yield stress of the corresponding layer and by assuming Holloman relation for stress–strain curve of each layer, the area under each stress–strain curve was acquired. Finally, by applying the rule of mixtures, Charpy impact energy of functionally graded steels in crack divider configuration was found through numerical method. The obtained results from the proposed model are in good agreement with those acquired from the experiments.

Application of ANFIS for analytical modeling of [formula omitted] of functionally graded steels

In the present study, fracture toughness (in terms of J I C ) of ferritic and austenitic functionally graded steel produced by electroslag remelting has been modeled in crack divider configuration by adaptive network-based fuzzy inference systems (ANFISs). To produce functionally graded steels, two slices of plain carbon steel and austenitic stainless steels were spot welded and used as electroslag remelting electrodes. Functionally graded steel containing graded layers of ferrite and austenite may be fabricated via diffusion of alloying elements during remelting stage. To build the model for graded ferritic and austenitic steels, training, testing and validation using respectively 174 and 120 experimental data were conducted. According to the input parameters, in the ANFIS model, the Vickers microhardness of each layer was predicted. A good fit equation which correlates the Vickers microhardness of each layer to its corresponding chemical composition was achieved by the optimized network for both ferritic and austenitic graded steels. Afterward, the Vickers microhardness of each layer was related to the yield stress of the corresponding layer and by assuming the Holloman relation for the stress–strain curve of each layer, the area under each stress–strain curve was acquired. Finally, by applying the rule of mixtures, fracture toughness of functionally graded steels in crack divider configuration was found through a numerical method. The obtained results from the proposed model are in good agreement with those acquired from the experiments.

Comparative Analysis of Linear and Nonlinear Methods of Estimating the Pseudo-Second-Order Kinetic Parameters for Sorption of Malachite Green onto Pretreated Rice Husk

ABSTRACT Batch sorption experiments were carried out for removal of malachite green from aqueous solution using pretreated rice husk. The equilibrium kinetic data were analyzed using pseudo-second-order kinetic model. A comparison between linear and nonlinear methods of estimating the kinetic parameters was carried out. Four pseudo-second-order kinetic linear equations were discussed. The coefficient of determination (r 2) and chi-square (χ2) test were employed as error analysis methods to determine the best-fitting equation. The results show that nonlinear method is a better alternative to obtain the kinetic parameters. In addition, the chi-square test was a better method to determine the best-fitting model.

Modeling of kinetics of pertechnetate removal by amino-functionalized glycidyl methacrylate copolymer

Technetium-99 comprises a significant health risk, since edible plants can bioaccumulate and convert it to more lipophilic species that cannot be excreted through urine. Batch kinetics of pertechnetate removal from aqueous solutions by two samples of crosslinked poly(glycidyl methacrylate-co-ethylene glycol dimethacrylate) functionalized with diethylene triamine (PGME-deta) was investigated at the optimum pH value of 3.0, and the initial solution activity of 325 MBq dm−3. PGME-deta was characterized by elemental analysis, mercury intrusion porosimetry, and scanning electron microscopy. Five kinetic models (pseudo-first, pseudo-second order, Elovich, Bangham, and intraparticle diffusion) were used to determine the best-fit equation for pertechnetate sorption. After 24 h, PGME-deta samples sorbed more than 98% of pertechnetate present, with maximum sorption capacity of 25.5 MBq g−1, showing good potential for remediation of slightly contaminated groundwater.

Normal Reference Ranges of Ductus Venosus Doppler Indices in the Period from 14 to 40 Weeks’ Gestation

Objective: To construct reference ranges of ductus venosus (DV) Doppler indices in normal singleton pregnancies. Methods: A cross-sectional study was conducted on low-risk singleton pregnancies with accurate gestational age, and normal fetuses were enrolled into the study. Measurements of DV Doppler indices were determined by experienced sonographers. Poor quality images were excluded. Results: A total of 640 fetuses underwent DV measurements, ranging from 13 to 30 for each gestational week. The relationship between gestational age and DV Doppler indices was not linear. The best-fit regression equations are as follows: preload index = (5.061 – 0.4882) × exp (–0.211 × GA) + 0.4882; peak velocity index for veins = (7.498 – 0.5609) × exp (–0.2184 × GA) + 0.5609; pulsatility index for veins = (17.9 – 0.6053) × exp (–0.2512 × GA) + 0.6053; systolic/atrial wave ratio = (300 – 2.124) × exp (–0.3649 × GA) + 2.124. Notably, during the period from 14 to 20 weeks’ gestation, all of the four indices rapidly decreased and they were relatively stable or slightly decreased after that. The nomogram tables for various percentile ranges were constructed. Conclusion: A nomogram for DV Doppler indices for each gestational week during the period from 14 to 40 weeks’ gestation was established. These reference ranges may be a useful non-invasive tool for evaluation of fetal cardiac function.

Effect of the graphite electrode material on the characteristics of molten salt electrolytically produced carbon nanomaterials

Abstract The electrochemical erosion of a graphite cathode during the electrolysis of molten lithium chloride salt may be used for the preparation of nano-structured carbon materials. It has been found that the structures and morphologies of these carbon nanomaterials are dependent on those of the graphite cathodes employed. A combination of tubular and spherical carbon nanostructures has been produced from a graphite with a microstructure of predominantly planar micro-sized grains and a minor fraction of more irregular nano-sized grains, whilst only spherical carbon nanostructures have been produced from a graphite with a microstructure of primarily nano-sized grains. Based on the experimental results, a best-fit regression equation is proposed that relates the crystalline domain size of the graphite reactants and the carbon products. The carbon nanomaterials prepared possess a fairly uniform mesoporosity with a sharp peak in pore size distribution at around 4 nm. The results are of crucial importance to the production of carbon nanomaterials by way of the molten salt electrolytic method.

Modeling a cascade of effects: the role of speed and executive functioning in preterm/full-term differences in academic achievement

This study identified deficits in executive functioning in pre-adolescent preterms and modeled their role, along with processing speed, in explaining preterm/full-term differences in reading and mathematics. Preterms (< 1750 g) showed deficits at 11 years on a battery of tasks tapping the three basic executive functions identified by Miyake - updating/working memory, inhibition, and shifting. Confirmatory factor analysis showed that these executive functions, though correlated, were distinct from one another and from processing speed, which later proved to account for much of the intercorrelation among executive functions. In the best-fitting structural equation model, the negative effects of prematurity on achievement were completely mediated by the three executive functions and speed in a cascade of effects: prematurity → slower processing speed → poorer executive functioning (working memory) → lower achievement in math and reading.

Verticillium wilt in nursery trees: damage thresholds, spatial and temporal aspects

Verticillium wilt can cause high losses in tree nurseries. To be able to predict disease and unravel disease dynamics over time and space, the relationship between verticillium wilt and soil inoculum densities of Verticillium dahliae and the nematode Pratylenchus fallax was studied in two 4-year field experiments with Acer platanoides and Catalpa bignonioides in the Netherlands. Best-fit regression equations showed that pre-planting inoculum densities of V. dahliae can be used to predict verticillium wilt over a period of at least 4 years. Pratylenchus fallax contributed significantly to disease severity in A. platanoides in some years. Disease can already occur at the detection limit of the pathogens. The 5% infection thresholds for V. dahliae were at 1 (A. platanoides) vs. 3 (C. bignonioides) colony-forming units (CFU) g−1 soil. Analysis of spatial relationships indicated that diseased plants had a higher influence on neighbouring plants at low V. dahliae inoculum densities (<5 CFU g−1 soil) than at high densities (≥5 CFU g−1 soil). Seventy-four percent of the diseased plants recovered during the following year. After that year, recovered plants had a significantly higher probability of becoming diseased again than plants that were healthy during the two previous years, at high inoculum densities of V. dahliae, indicating that inoculum density in the soil, rather than incomplete recovery, was the most important factor for disease development.

Pseudo-second-order kinetic models for the sorption of malachite green onto Tamarindus indica seeds: Comparison of linear and non-linear methods

In this study, the sorption of malachite green, a basic dye onto Tamarindus indica seed was studied by performing batch kinetic sorption experiments. The equilibrium kinetic data were analyzed using the pseudo-second-order kinetic model. A comparison between linear least-squares method and non-linear regression method of estimating the kinetic parameters was examined. Four pseudo-second-order kinetic linear equations were discussed. The coefficient of determination (r 2), average relative error (ARE) and the chi-square (χ 2) test were employed as error analysis methods to determine the best-fitting equation. Kinetic parameters obtained from four kinetic linear equations using the linear method differed but they were the same when non-linear method was used. Type 1 pseudo-second-order kinetic model very well represented the kinetic uptake of malachite green by Tamarindus indica seeds while Type 4 exhibited the worst fit. Present investigation showed that the non-linear method may be a better way to determi...

Above- and belowground biomass in a Brazilian Cerrado

Cerrado is a biome that occupies about 25% of the Brazilian territory and is characterized by a gradient of grassland to savanna and forest formations and by high species richness. It has been severely affected by degradation and deforestation and has been heavily fragmented over the past 4–5 decades. Despite the recognized overall ecological importance of the Cerrado, there are only few studies focusing on the quantification of biomass in this biome. We conducted such a case study in the South-East of Brazil in a cerrado sensu stricto (cerrado s.s.) with the goal to produce estimates of above- and belowground biomass and to develop allometric equations. A number of 120 trees from 18 species were destructively sampled and partitioned into the components: leaves, branches and bole. Five models with DBH ( D), height ( H), D 2 H and wood density ( WD) as independent variables were tested for the development of allometric models for individual tree aboveground biomass (leaves + branches + bole). One model based on basal area (BA) as a stand parameter was also tested as an alternative approach for predicting aboveground biomass in the stand level. Belowground biomass was estimated by subsampling on 10 sample plots. Mean aboveground tree biomass (bole, branches and leaves) was estimated to be 62,965.5 kg ha −1( SE = 14.6%) and belowground biomass accounted for 37,501.8 kg ha −1 ( SE = 23%). The best-fit equation for the estimation of individual tree aboveground biomass include DBH and wood density as explanatory variables ( R 2 = 0.898; SEE = 0.371) and is applicable for the diameter range of this study (5.0–27.6 cm) and in environments with similar conditions of the cerrado s.s. sampled. In the stand level, the model tested presented a higher goodness of fit than the single tree models ( R 2 = 0.934; SEE = 0.224). Our estimates of aboveground biomass are higher than reported by other studies developed in the same physiognomy, but the estimates of belowground biomass are within the range of values reported in other studies from sites in cerrado s.s. Both biomass estimates, however, exhibit relatively large standard errors. The root-to-shoot ratio of the sample trees is in the magnitude of reported values for savanna ecosystems, but smaller than estimated from other studies in the cerrado s.s.

Adsorption of basic dyes by dried waste sludge: Kinetic, equilibrium and desorption studies

Dried waste sludge was used as adsorbent to remove methylene blue, crystal violet and basic fuchsine using batch systems. Rate experiments were performed at various initial adsorbate concentrations, adsorbent concentration and reaction temperature. The experimental data were analyzed using several kinetic equations to determine the best-fit equation and related parameters were calculated. It was shown that the adsorption of respective dye could be best described by Ho’s pseudo second order equation. The intraparticle diffusion played an important role in adsorption process. Effect of various initial adsorbent concentration and ionic strength on equilibrium was also investigated. Langmuir and Freundlich isotherms were applicable to the adsorption process and their constants were evaluated. Langmuir isotherm was found to be more suitable than Freundlich isotherm for correlation of equilibrium data. An increase in ionic strength exhibited an adverse effect on respective dye uptake. Desorption experiments sho...

Prediction of Parenteral Nutrition Osmolarity by Digital Refractometry

Infusion of high-osmolarity parenteral nutrition (PN) formulations into a peripheral vein will damage the vessel. In this study, the authors developed a refractometric method to predict PN formulation osmolarity for patients receiving PN. Nutrients in PN formulations were prepared for Brix value and osmolality measurement. Brix value and osmolality measurement of the dextrose, amino acids, and electrolytes were used to evaluate the limiting factor of PN osmolarity prediction. A best-fit equation was generated to predict PN osmolarity (mOsm/L): 81.05 × Brix value--116.33 (R(2) > 0.99). To validate the PN osmolarity prediction by these 4 equations, a total of 500 PN admixtures were tested. The authors found strong linear relationships between the Brix values and the osmolality measurement of dextrose (R(2) = 0.97), amino acids (R(2) = 0.99), and electrolytes (R(2) > 0.96). When PN-measured osmolality was between 600 and 900 mOsm/kg, approximately 43%, 29%, 43%, and 0% of the predicted osmolarity obtained by equations 1, 2, 3, and 4 were outside the acceptable 90% to 110% confidence interval range, respectively. When measured osmolality was between 900 and 1,500 mOsm/kg, 31%, 100%, 85%, and 15% of the predicted osmolarity by equations 1, 2, 3, and 4 were outside the acceptable 90% to 110% confidence interval range, respectively. The refractive method permits accurate PN osmolarity prediction and reasonable quality assurance before PN formulation administration.

Improving Tree Age Estimates Derived from Increment Cores: A Case Study of Red Pine

Abstract Accurate tree ages are critical to a range of forestry and ecological studies. However, ring counts from increment cores, if not corrected for the years between the root collar and coring height, can produce sizeable age errors. The magnitude of errors is influenced by both the height at which the core is extracted and the growth rate. We destructively sampled saplings and small trees of red pine (Pinus resinosa Ait.) and combined within- and between-tree cross-dating to determine accurate rings counts and radial growth rates for 11 stem sections of each sample. We developed regression models to estimate age adjustment as a function of coring height and radial growth rate. We compared candidate models using corrected Akaike's information criterion scores, and we evaluated model performance by jackknife permutations. Application of our best-fit equations clearly improved age estimates: compared with unadjusted ring counts, our adjusted age estimates had normally distributed errors centered near 0, lower standard deviations, and a narrower range of values. Thus, these equations can be used to adjust ages of cored, mature trees occurring in these same settings. The methods used here may be applied to other shade-intolerant or mid-tolerant species where improved tree establishment dates are needed.

Fetal cardiac dimensions at 14–40 weeks' gestation obtained using cardio‐STIC‐M

To establish normative reference ranges of fetal cardiac dimensions derived from volume datasets acquired using spatiotemporal image correlation with M-mode display (cardio-STIC-M). A cross-sectional study was undertaken on singleton pregnancies with normal fetuses and accurate gestational ages. Cardio-STIC volume datasets were acquired by experienced operators using a high-resolution ultrasound machine; these were maneuvered to obtain a four chamber-view with exactly horizontal interventricular septum (IVS). Cardiac dimensions were measured in STIC-M-mode using 4D View software. A total of 657 measurements, at a rate of between 15 and 37 per week, were obtained. Normal reference ranges for biventricular outer diameter, left and right ventricular inner diameter, left and right ventricular wall thickness, IVS thickness, left to right ventricular diameter ratio and left and right ventricular shortening fractions were constructed based on best-fit equations as a function of gestational age, fetal head circumference and biparietal diameter. Thirty-four volume datasets of abnormal fetal hearts were also separately assessed, many of which showed abnormal cardiac dimensions. This is the first report on normal ranges of fetal cardiac dimensions constructed using the new cardio-STIC-M technology. Preliminary evaluation suggests that these reference ranges may be a useful tool in the assessment of fetal cardiac abnormalities.

Reference ranges of fetal aortic and pulmonary valve diameter derived by STIC from 14 to 40 weeks of gestation

To develop reference ranges of fetal aortic and pulmonary valve diameter derived from volume datasets of spatio-temporal image correlation (STIC). A cross-sectional study was undertaken on low-risk pregnancies with well-established data from 14 to 40 weeks. Volume datasets of STIC were acquired for subsequent off-line analysis. Aortic and pulmonary valve diameters were measured in STIC multiplanar view using 4D-View version 9. Normal Z scores and centile reference ranges were constructed from these measurements against gestational age (GA) and biparietal diameter (BPD) as independent variables, using regression models for both mean and SD. A total of 606 volume datasets were successfully measured. Normal reference ranges for predicting mean values and SD of aortic and pulmonary valve diameter were constructed based on best-fit equations (linear function) as follows: mean aortic diameter (mm) was modeled as a function of GA (weeks) and BPD (mm) as - 2.4838 + 0.2702 × GA, (SD = 0.1482 + 0.0156 × GA) and - 1.5952 + 0.0989 × BPD (SD = 0.1672 + 0.00572 × BPD). Mean pulmonary diameter was modeled as - 2.5924 + 0.2935 × GA (SD = 0.2317 + 0.01524 × GA) and - 1.6830 + 0.1083 × BPD (SD = 0.1971 + 0.0059 × BPD). We have provided nomograms and Z scores of fetal aortic and pulmonary valve diameters. These reference ranges may be a useful tool in the assessment of fetal cardiac abnormalities.

Is Radiographic Measurement of Bony Landmarks Reliable for Lateral Meniscal Sizing?

Background: The accuracy of meniscal measurement methods is still in debate. Hypothesis: The authors’ protocol for radiologic measurements will provide reproducible bony landmarks, and this measurement method of the lateral tibial plateau will correlate with the actual anatomic value. Study Design: Controlled laboratory study. Methods: Twenty-five samples of fresh lateral meniscus with attached proximal tibia were obtained during total knee arthroplasty. Each sample was obtained without damage to the meniscus and bony attachment sites. The inclusion criterion was mild to moderate osteoarthritis in patients with mechanical axis deviation of less than 15°. Knees with lateral compartment osteoarthritic change or injured or degenerated menisci were excluded. For the lateral tibial plateau length measurements, the radiographic beam was angled 10° caudally at neutral rotation, which allowed differentiation of the lateral plateau cortical margins from the medial plateau. The transition points were identified and used for length measurement. The values of length were then compared with the conventional Pollard method and the anatomic values. The width measurement was done according to Pollard’s protocol. For each knee, the percentage deviation from the anatomic dimension was recorded. Intraobserver error and interobserver error were calculated. Results: The deviation of the authors’ radiographic length measurements from anatomic dimensions was 1.4 ± 1.1 mm. The deviation of Pollard’s radiographic length measurements was 4.1 ± 2.0 mm. With respect to accuracy—which represents the frequency of measurements that fall within 10% of measurements—the accuracy of authors’ length was 98%, whereas for Pollard’s method it was 40%. There was a good correlation between anatomic meniscal dimensions and each radiologic plateau dimensions for lateral meniscal width (R 2 = .790) and the authors’ lateral meniscal length (R 2 = .823) and fair correlation for Pollard’s lateral meniscal length (R 2 = .660). The reliability of each radiologic measurement showed good reliability (intraclass correlation coefficients, .823 to .973). The authors tried to determine the best-fit equation for predicting meniscal size from Pollard’s method of bone size, as follows: anatomic length = 0.52 × plateau length (according to Pollard’s method) + 5.2, not as Pollard suggested (0.7 × Pollard’s plateau length). Based on this equation—namely, the modified Pollard method—the percentage difference decreased, and the accuracy increased to 92%. Conclusion: Lateral meniscal length dimension can be accurately predicted from the authors’ radiographic tibial plateau measurements. Clinical Relevance: This study may provide valuable information in preoperative sizing of lateral meniscus in meniscal allograft transplantation.

Kinetics of Pb (II) adsorption on black carbon derived from wheat residue

The kinetics of Pb (II) adsorption onto black carbon (BC) has been investigated. The BC samples were characterized by the techniques of X-ray diffraction (XRD), scanning electron microscope equipped with the energy dispersive X-ray spectroscope (SEM-EDS) and Fourier transform-infrared spectroscopy (FTIR). Some characteristic parameters including specific surface area, point of zero point and surface acidity/basicity were also determined. The experimental data was analyzed using various adsorption kinetic models – pseudo-first order, the Ritchie second order, the modified second order, the Elovich and the parabolic diffusion models – to determine the best-fit equation for the adsorption of metal ions onto BC. The results show that the modified Ritchie second order equation and Elovich equation fitted the experimental data well. Also, the parabolic diffusion model fitted the experimental data well at the initial stage of adsorption (<60min), indicating that the process of Pb (II) adsorption by BC was diffusion-controlled.

Pseudo-Second-Order Kinetic Model for Biosorption of Methylene Blue onto Tamarind Fruit Shell: Comparison of Linear and Nonlinear Methods

ABSTRACT In this study, the sorption of methylene blue, a basic dye, onto tamarind fruit shell was studied by performing batch kinetic sorption experiments. The equilibrium kinetic data were analyzed using the pseudo-second-order kinetic model. A comparison between linear least squares method and nonlinear regression method of estimating the kinetic parameters was examined. Four pseudo-second-order kinetic linear equations were discussed. The coefficient of determination (r 2), and the chi-square (χ2) test were employed as error analysis methods to determine the best-fitting equation. Kinetic parameters obtained from four kinetic linear equations using the linear method differed but they were the same when nonlinear method was used. Present investigation showed that by linear method a Type 1 expression very well represent the kinetic uptake of methylene blue onto tamarind fruit shell. Linear method was found to check only the hypothesis instead of verifying the kinetic model. Nonlinear regression method was found to be the more appropriate method to determine the rate kinetic parameters.

Effects of Stocking Density on Growth Performance of Thai Abalone,Haliotis asinina,Linnaeus 1758, Reared Under a Semiclosed Recirculating Land-Based System

The effect of stocking density on growth performance of Thai abalone, Haliotis asinina, Linnaeus 1758, was investigated over an 8-mo period (July 2008 to March 2009). A semiclosed recirculating land-based system was used with stocking densities of 368, 735, and 1,100 individuals/m2. Each stocking density had 3 replicates. An artificial diet, modified from a shrimp commercial diet, was used throughout this experiment. In July 2008, initial sizes of abalone (mean shell length (SL) ± SE) were not statistically different, with values of 1.28 ± 0.0062, 1.28 ± 0.0131, and 1.30 ± 0.0339 cm for 368, 735, and 1,100 individuals/m2, respectively (P > 0.05). After 8 mo, SLs were significantly different, with values of 3.63 ± 0.092, 3.25 ± 0.1173, and 3.05 ± 0.0985 cm for the 3 stocking densities. As the stocking density increased, mean specific growth rates, measured by the percent increase in SL during the 8-mo period, decreased, with values (mean ± SD) of 1.97 ± 0.0495, 1.66 ± 0.1595, and 1.53 ± 0.0544. The mean specific growth rate of the density 368 individuals/m2 was significantly different from 735 individuals/m2 and 1,100 individuals/m2. The variations of specific growth rate, calculated in term of the coefficient of variation (mean ± SD) were increased with increasing stocking densities: 20.16 ± 0.251, 22.17 ± 3.146, and 23.66 ± 0.886. The difference was significant only between the 368 individuals/ m2 and the 1,100 individuals/m2. The best-fit linear equations between the natural logarithm of specific growth rate and initial size of abalone for 3 stocking densities were estimated. These equations demonstrated that specific growth rates of the larger size abalone decreased at higher rates than that of the smaller size as the stocking density increased. This demonstrated a nonrandom effect of stocking density on abalone size. This also implied that grading of large abalone should be done regularly. Allometric equations between shell width (SW) and SL as well as between total weight (TW) and SL were calculated: SW = 0.6531 SL0.777 (r2 = 0.721) and TW = 0.3276 SL2.720 (r2 = 0.823), respectively. Throughout this 8-mo experiment, survival rates of abalone were not significantly different, with values of 95.1 ± 5.05, 92.9 ± 6.19, and 95.7 ± 0.513 at stocking densities of 368, 735, and 1,100 individuals/m2, respectively.

The incidence of malaria and the comparison of hematological and biochemical indices of Plasmodium falciparum‐parasitemic and aparasitemic sickle cell disease (SCD) patients

Hemolytic anemia is common in sickle cell disease (SCD), but the course and extent differ, depending on genetic, epigenetic, and environmental factors. In the malaria-endemic tropical environment, some vulnerable subjects would be infected and the impact of infection would vary. Therefore, this study was to find malaria incidence and the associated changes in some laboratory indices in 330 SCD subjects. Following blood smear preparation for falciparum detection, hematological and biochemical indices were measured for a comparison of parasitemic and age-matched, genotype-matched, and sex-matched nonparasitemics. For sixty-nine parasitemics, constituting about 21% of all subjects studied, and sixty-six matched nonparasitemics, hematological indices (hemoglobin, white-cell count, red-cell count, mean cellular volume, reticulocyte count, and HbF) as well as biochemical indices (LDH, total bilirubin, AST, and ALT) were determined. For all quantities, except the reticulocyte count (12.3% ± 12.4% for parasitemics and 23.6% ± 17.7% for nonparasitemics), no statistically significant differences were observed. Classification of both cohorts according to their genotypes showed some intergenotypic differences for hemoglobin and WBC counts. Mathematical modeling of the reticulocyte counts shows the distribution in the parasitemics followed an exponential pattern, while the nonparasitemic showed a polynomial distribution, with each model characterized by an equation of best fit. The study has shown about 21% incidence of parasitemia. All differences in the indices can be seen as normal variations, unattributable to the malaria infection. However, the lower reticulocyte count in the parasitemic is a reflection of lowered erythropoietic activity because of the infection.