Kinetics Modeling on the Biosorption of Remazol Black B Dye by Aspergillus flavus

Azo dyes, such as Remazol Black B, are different from conventional dyes in that they establish covalent bonds with textile fibers like cotton. They are widely utilized in the textile industry because of their favorable properties of bright color, water resistance, simple application procedures, and low energy consumption. Their discharge into receiving streams has major environmental consequences, such as reducing photosynthesis in aquatic life due to lower light penetration. The biosorption isotherm data of Remazol Black B dye biosorption by Aspergillus flavus were investigated using two models—pseudo-1st order and pseudo-2nd order—and fitted using non-linear regression. The pseudo-1st order model was found to be the best by statistical analysis using 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). At 250 mg/L, kinetic analysis using the pseudo-1st order model yielded an equilibrium sorption capacity qe of 4.61 mg/g (95 % confidence interval from 4.54 to 4.68) and a pseudo-1st-order rate constant, k1 of 0.15 (95% C.I. from 0.128 to 0.164).

Kinetic Analysis of the Adsorption of Ethyl Violet onto Graphene Oxide Sheets Integrated with Gold Nanoparticles

An example of biosorption is when the sorbent is made from a biodegradable material. Biosorption is now being seen as a simple, cost-effective, and environmentally acceptable alternative to traditional pollution treatment methods. Bioremediation is one of the branches of bioremediation that is used to minimise pollution in the context of incorrect dye waste disposal. The sorption isotherm of Ethyl Violet onto graphene oxide were analyzed using three models—pseudo-1st, pseudo-2nd and Elovich, and fitted using non-linear regression. 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-second-order model was the best which was the same finding from the original published work. The calculated evidence ratio was 11 with an AICc probability value of 0.91 indicating that the best model was at least 11 times better than the nearest best model, which was pseudo-1st. Further analysis is needed to provide proof for the mechanism usually tied to this kinetic. Nonlinear regression analysis using the pseudo-2nd order model for the highest concentration tested, which was 10 mM, gave values of equilibrium sorption capacity qe of 30.928 mg/g (95% confidence interval from 29.328 to 32.527) and a value of the pseudo-2nd-order rate constant, k2 of 0.020 (95% confidence interval from 0.011 to 0.028).

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 Malachite Green onto Graphene Oxide Sheets Integrated with Gold Nanoparticles

Malachite green is extensively used in the textile dye industry and in agriculture as fish pests’ pesticide. Biosorption is a type of sorption technique that uses a biological sorbent. As of now, biosorption is viewed as a simple and cost-effective process that might be used as an alternative to traditional pollution treatment methods. Bioremediation is one of the branches of bioremediation that is used to minimise pollution in the context of incorrect textile waste disposal. The sorption isotherm of Malachite Green onto graphene oxide 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.

Harmonizing labeling and analytical strategies to obtain protein turnover rates in intact adult animals.

Changes in the abundance of individual proteins in the proteome can be elicited by modulation of protein synthesis (the rate of input of newly synthesized proteins into the protein pool) or degradation (the rate of removal of protein molecules from the pool). A full understanding of proteome changes therefore requires a definition of the roles of these two processes in proteostasis, collectively known as protein turnover. Because protein turnover occurs even in the absence of overt changes in pool abundance, turnover measurements necessitate monitoring the flux of stable isotope labeled precursors through the protein pool such as labeled amino acids or metabolic precursors such as ammonium chloride or heavy water. In cells in culture, the ability to manipulate precursor pools by rapid medium changes is simple, but for more complex systems such as intact animals, the approach becomes more convoluted. Individual methods bring specific complications, and the suitability of different methods has not been comprehensively explored. In this study we compare the turnover rates of proteins across four mouse tissues, obtained from the same inbred mouse strain maintained under identical husbandry conditions, measured using either [13C6]lysine or [2H2]O as the labeling precursor. We show that for long-lived proteins, the two approaches yield essentially identical measures of the first order rate constant for degradation. For short-lived proteins, there is a need to compensate for the slower equilibration of lysine through the precursor pools. We evaluate different approaches to provide that compensation. We conclude that both labels are suitable, but careful determination of precursor enrichment kinetics in amino acid labeling is critical and has a considerable influence on the numerical values of the derived protein turnover rates.

Production and loss of O2(1Δg) at atmospheric pressure using microwave-driven microplasmas

We have used arrays of microwave-generated microplasmas operating at atmospheric pressure to generate high concentrations of singlet molecular oxygen, O2(1Δg), which is of interest for biomedical applications. The discharge is sustained by a pair of microstrip-based microwave resonator arrays which force helium/oxygen gas mixtures through a narrow plasma channel. We have demonstrated the efficacy of both NO and less-hazardous N2O additives for suppression of ozone and associated enhancement of the O2(1Δg) yield. Quenching of O2(1Δg) by ozone is sufficiently suppressed such that quenching by ground state molecular oxygen becomes the dominant loss mechanism in the post-discharge outflow. We verified the absence of other significant gas-phase quenching mechanisms by measuring the O2(1Δg) decay along a quartz flow tube. These measurements indicated a first-order rate constant of (1.2 ± 0.3) × 10-24 m3 s−1, slightly slower than but consistent with prior measurements of singlet oxygen quenching on ground state oxygen. The discharge-initiated reaction mechanisms and data analysis are discussed in terms of a chemical kinetics model of the system.

Visual Interpretation of the Meaning of kcat/KM in Enzyme Kinetics

kcat and kcat/KM are the two fundamental kinetic parameters in enzyme kinetics. kcat is the first-order rate constant that determines the reaction rate when the enzyme is fully occupied at a saturating concentration of the substrate. kcat/KM is the second-order rate constant that determines the reaction rate when the enzyme is mostly free at a very low concentration of the substrate. Both parameters provide critical information on how the enzyme lowers the energy barriers along the reaction pathway for catalysis. However, it is surprising how often kcat/KM is used inappropriately as a composite parameter derived by dividing kcat with KM to assess both catalytic power and affinity to the substrate of the enzyme. The main challenge in explaining the true meaning of kcat/KM is the difficulty to demonstrate how the reaction energetics of enzyme catalysis determines kcat/KM in a simple way. Here, I report a step-by-step demonstration on how to visualize the meaning of kcat/KM on the reaction energy diagram. By using the reciprocal form of the expression of kcat/KM with the elementary rate constants in kinetic models, I show that kcat/KM is a harmonic sum of several kinetic terms that correspond to the heights of the transition states relative to the free enzyme. Then, I demonstrate that the height of the highest transition state has the dominant influence on kcat/KM, i. e. the step with the highest transition state is the limiting step for kcat/KM. The visualization of the meaning of kcat/KM on the reaction energy diagram offers an intuitive way to understand all the known properties of kcat/KM, including the Haldane relationship.

Evaluation of borinic acids as new, fast hydrogen peroxide–responsive triggers

Hydrogen peroxide (H2O2) is responsible for numerous damages when overproduced, and its detection is crucial for a better understanding of H2O2-mediated signaling in physiological and pathological processes. For this purpose, various “off–on” small fluorescent probes relying on a boronate trigger have been prepared, and this design has also been involved in the development of H2O2-activated prodrugs or theranostic tools. However, this design suffers from slow kinetics, preventing activation by H2O2 with a short response time. Therefore, faster H2O2-reactive groups are awaited. To address this issue, we have successfully developed and characterized a prototypic borinic-based fluorescent probe containing a coumarin scaffold. We determined its in vitro kinetic constants toward H2O2-promoted oxidation. We measured 1.9 × 104m−1⋅s−1 as a second-order rate constant, which is 10,000-fold faster than its well-established boronic counterpart (1.8 m−1⋅s−1). This improved reactivity was also effective in a cellular context, rendering borinic acids an advantageous trigger for H2O2-mediated release of effectors such as fluorescent moieties.

Application of polymer-coated Macadamia integrifolia nutshell biomass impregnated with palladium for chromium(VI) remediation

Freely suspended and porous basket restrained granules of palladium nanoparticles supported on polymer-grafted Macadamia nutshell biomass (Pd@Polym-MNS) composite were used for the treatment chromium(VI)-containing water. In the presence of formic acid, the Pd@Polym-MNS demonstrated its activity in the adsorption-reduction-based conversion of noxious chromium(VI) to less toxic chromium(III) with a low activation energy of 13.4 kJ mol–1, ΔH0 (+ 10.8 kJ mol–1), ΔS0 (−270.0 J mol–1 K–1), and ΔG0 (+ 91.3 to + 98.0 kJ mol–1) indicated the exothermic, endergonic and non-spontaneous nature of the catalytic redox reaction. In addition to facilitating easy recovery, rinsing, and reuse, restraining the Pd@Polym-MNS in the basket reactor helped maintain the integrity of the catalysts by preventing violent collisions of suspended granules with the mixing apparatus and the walls of the reaction vessel. Whereas the pseudo-first-order rate constant was recorded as 0.157 min–1 upon initial use, values of the mean and relative standard deviation for the second, third and fourth consecutive uses were found to be 0.219 min–1 and 1.3%, respectively. According to a response surface methodological approach to batch experimentation, the initial concentration of chromium(VI) and catalyst dosage had the greatest impact on the redox reaction rate, accounting for 85.7% and 11.6% of the variability in the value of the pseudo-first-order rate constant, respectively. Mutually beneficial effects of the combinations of high formic acid and low chromium(VI) concentration, high temperature and catalyst dosage as well as high formic acid and catalyst dosage were recorded.