Testing for the Equality of Variance for the Four-parameter Logistic (4PL) Model for the Detection of Vibrio cholerae DNA with Polystyrene-coacrylic Acid Composite Nanospheres

When it comes to finding the best fit of nonlinear curves to acceptable models, linear regression with least squares is the most effective technique. Because residuals (the difference between observed and predicted data) must follow a normal distribution and the data must be free of outliers and uniform variance, statistical tests are used to identify the most appropriate model for a given situation (homoscedasticity). If all of these characteristics are satisfied, the system is said to be robust. In parametric nonlinear regression, one of the numerous assumptions is that the within-group variances of the groups are all the same, which is one of several assumptions (exhibit homoscedasticity). If the variances vary from one another (show heteroscedasticity), then the model is not statistically competent to describe the data as a whole. Data on the detection of Vibrio cholerae DNA with polystyrene-coacrylic acid composite nanospheres as modelled using the nonlinear four-parameter logistic (4PL) regression was preliminary check for homogeneity of variance using the Bartlett’s and Levene’s tests. It was found that the critical value of 2 was 28.869, according to Bartlett's test findings. Excel's CHIDIST function yielded a probability of 0.389 (not significant), suggesting that the variances of the residuals did not change significantly. The p-value for Levenes's test was 0.917, indicating that there were no distinct changes between the residual variances meaning that the use of the 4-PL model in fitting the data was adequate statistically.

Isolation of A Molybdenum-reducing Bacillus sp. strain Zeid 15 and Modeling of its Growth on Amides

More and more people are looking at bioremediation as a cheaper option to physhiochemical techniques for cleaning up pollution from farming, mines, and other chemical industries. Toxic effects of molybdenum on spermatogenesis harm not only humans but also livestock and aquatic life. As a result, efforts are being made to remove it from the ecosystem. A microorganism that can convert soluble molybdenum into colloidal molybdenum blue has been discovered. Phosphate concentrations were optimum between 2.5 and 5, molybdate concentrations between 15 and 20, pH between 6, and temperature between 25 and 34 degrees Celsius for the bacteria to thrive. Absorption spectrum of Mo-blue shows a peak at 865 nm and a shoulder at 700 nm, which indicates that it is in fact reduced phosphomolybdate. Copper, mercury, silver, copper, and chromium are all hazardous heavy metals that hinder the synthesis of Mo-blue. Bacillus sp. strain Zeid 15 is the most likely candidate for the bacterium's identity. As part of our screening, we look for the bacterium's capacity to employ different nitriles and amides as potential electron donors for molybdenum reduction or as substrates for growth. A microplate format was used for the screening. The bacterium was able to use the amides acrylamide and propionamide as sources of electron donor for reduction. Mo-blue production was best supported by acrylamide between 750 and 1250 mg/L, and propionamide between 750 and 1000 mg/L. In addition, these amides including acetamide could support the growth of the bacterium. The modified Gompertz model was utilized to model the growth of this bacterium on amides. The model’s growth parameters obtained were lag periods of 1.372, 1.562 and 1.639 d and maximum specific growth rates of 1.38, 0.95 and 0.734 d-1, for acrylamide, acetamide and propionamide, respectively. The capacity of this bacterium to decontaminate simultaneously amides and molybdenum is a novel characteristic that will be very beneficial in bioremediation.

Kinetic Analysis of the Adsorption of Cibacron Blue onto Bean Peel

Biosorption is a kind of sorption technology in which the sorbent is derived from a biological source. At the moment, biosorption is seen as a simple, cost-effective, and environmentally friendly process that might be employed as a viable alternative to conventional techniques of pollution removal. When it comes to improper textile waste disposal, it falls under one of the branches of bioremediation that is used to reduce contamination in the setting of improper textile waste disposal. The sorption isotherm of Cibacron Blue onto bean peel were analyzed using three models—pseudo-1st, pseudo-2nd and Elovich, and fitted using non-linear regression. The Elovich model was the poorest in fitting the curve based on visual observation and the best was pseudo-2nd order based on statistical analysis such as root-mean-square error (RMSE), adjusted coefficient of determination (adjR2), bias factor (BF), accuracy factor (AF), corrected AICc (Akaike Information Criterion), Bayesian Information Criterion (BIC) and Hannan–Quinn information criterion (HQC). Nonlinear regression analysis using the pseudo-2nd order model gave values of equilibrium sorption capacity qe of 6.164 mg/g (95% confidence interval from 5.918 to 6.410 ) and a value of the pseudo-2nd-order rate constant, k2 of 0.034 (95% confidence interval from 0.024 to 0.045). Further analysis is needed to provide proof for the chemisorption mechanism usually tied to this kinetic.

Kinetic Analysis of the Adsorption of Chromium onto Calcium Alginate Nanoparticles

The widespread use of chromium in industrial applications such as leather tanning, metallurgy, electroplating, and refractory materials has resulted in it being one of the most harmful trace elements to be introduced into surface and ground waters. The sorption isotherm of chromium sorption onto calcium alginate nanoparticles were analyzed using three models—pseudo-1st, pseudo-2nd and Elovich, and fitted using non-linear regression. The Elovich model was the poorest in fitting the curve based on visual observation followed by the pseudo-1st order. Statistical analysis based on root-mean-square error (RMSE), adjusted coefficient of determination (adjR2), bias factor (BF), accuracy factor (AF), corrected AICc (Akaike Information Criterion), Bayesian Information Criterion (BIC) and Hannan–Quinn information criterion (HQC) that showed that the pseudo-1ST order model is the best model. Kinetic analysis using the pseudo-1st order model at 400 mg/L 4-BDE gave a value of equilibrium sorption capacity qe of 31.89 mg g-1 (95% confidence interval from 30.37 to 33.42) and a value of the pseudo-1st-order rate constant, k1 of 0.22 (95% confidence interval from 0.019 to 0.025). Further analysis is needed to provide proof for the chemisorption mechanism usually tied to this kinetic.

Optimization of Process Conditions for Effective Degradation of Azo Blue Dye by Streptomyces sp. DJP15: A Secondary Modelling Approac

The well function of aquatic and soil organisms including terrestrial, as well as those of all other living things, can be jeopardized if dyes aren't properly treated, as their degradation might lead to carcinogenic chemicals. Complete mineralization of dye is the only option, and this can be done using microorganisms. The azo blue dye inhibitory effect to its biodegradation by Streptomyces DJP15 was modelled using several inhibition kinetic models such as Haldane, Monod, Luong, Aiba, Teissier-Edwards, Han-Levenspiel and Yano. The result shows that only the Luong model failed to fit the data. The rest of the models visually ft the data although data fitting is problematic with datapoints of less than 10, which the result in this work demonstrates where it is not easy to choose the best model where nearly all of the models fit the data in a similar manner. Resorting to statistical discriminatory function, the best model was Monod with the smallest RMSE and AICc values and the highest adjR2 values and values for AF and BF close to unity. However, Monod has only two parameters and is the most robust. The Monod’s parameters were maximum specific degradation rate of 0.431 (1/h) (95% confidence interval from 0.391 to 0.456) and concentration of substrate giving half maximal rate or Ks value of 0.0001 (mg/L) (95% C.I. from -0.01 to 12.12). The confidence interval value for the Ks value was very large indicating poor data quality. This should be an important consideration in future works where the data point number can be increased to improve model fitting exercise.

Performance of Strobilanthes crispus Leaves Extract as Potential Antioxidant Compound in Oil-in-water Emulsion

Excess of free radicals accelerates the degradation of oil-in-water (O/W) emulsion due to oxidative damage resulting in low emulsion quality such as in lotion formulation. The blend of antioxidants in O/W emulsion could reduce the damage caused by the radical compounds. The crude extract of Strobilanthes crispus (S. crispus) leaves was screened for assessing bioactive phytochemical constituents. By using various chemical assays, the extract of S. crispus leaves revealed the presence of tannins, steroids, flavonoids, terpenoids and glycosides. Besides that, the antioxidant activity of the leaf extract, spray-dried extract, a lotion containing extract and other local and abroad commercial lotions were determined as references using standard methods such as total phenolic content (TPC), total flavonoid content (TFC), 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay and reducing power assay. In terms of TFC, the highest, 10.591±0.01 mg QE/g was recorded in crude extract along with the highest reducing power and percentage inhibition, 25.40±0.02 mg GAE/g and 88.89 % respectively. The result from TPC value can be a good indicator for a longer shelf life of the O/W emulsion if compared to other results from TPF, reducing power and DPPH value. From this study, it can be concluded that S. crispus has potential as a good natural antioxidant ingredient for the emulsion of O/W formulation.