Range Of pH Values Research Articles

Synergistic effects of oxygen vacancies and heterostructures for visible-light-driven photoreduction of uranium

Photocatalytic technology can reduce easily soluble U(VI) to insoluble U(IV) particles to realize the separation of uranium. However, the complex composition in seawater or the organic matter in uranium-containing wastewater severely restricts the separation of U(VI). Herein, a C3N4-CeO2-x heterojunction with abundant oxygen vacancies was constructed for the photoreduction of U(VI) in organic radioactive wastewater under visible light. Kinetic characterization and density functional theory (DFT) imply that the photoelectrons were transferred from g-C3N4 to CeO2-x through the built-in electric field generated by the heterostructure and were trapped by shallow traps generated by surface vacancies to achieve spatial separation. The tremendously enhanced separation rates and lifetime (∼125 %) of photoinduced carriers grant the exceptionally improved photocatalytic activity for U(VI) reduction (up to a 39-fold increase over the bulk g-C3N4). The as-prepared C3N4-CeO2-x exhibits good resilience to a variety of competing ions and over a wide range of pH values, thus it maintains excellent performance in uranium-spiked seawater and the organics (RhB) contained water. X-ray absorption fine structure (XAFS) analysis reveals that the reduction and inner-sphere surface complexation contributed to uranium immobilization. This work provides a new strategy for the separation of uranium from organic radioactive wastewater.

Prediction of peptide-induced silica formation under a wide pH range by molecular descriptors

Silica nanoparticles have demonstrated broad applicability from wastewater treatment to medicine. By increasing intermolecular interaction of silica precursor, peptides can induce the formation of biosilica usually under neutral and basic but not acidic conditions, and here, they are defined as silica-forming peptides (SFPs). In addition, the silica-forming capability of most putative SFPs has not been evaluated. To address both questions, we developed molecular descriptors to simulate and predict the silica-forming capabilities of SFPs under a wide range of pH values. We used van der Waals and electrostatic interactions as molecular descriptors to probe the physisorption between amino acid residues and proto-silicate. We then performed multiple-dimensional simulations using the canonical R5 peptide and three novel SFPs from the brown alga Sargassum fusiforme. Finally, we experimentally validated the silica-forming capability of the four SFPs at pH values from 4 to 8. Our results showed that the molecular descriptors provide accurate predictions on the adsorption of proto-silicate by SFPs. Thus, the method can be used to screen SFPs that are capable of inducing the formation of silica in a wide pH range more importantly including acidic conditions.

Characterization of a novel GH10 alkali-thermostable xylanase from a termite microbiome

The aim of the present study was to assess the biochemical and molecular structural characteristics of a novel alkali-thermostable GH10 xylanase (Xyl10B) identified in a termite gut microbiome by a shotgun metagenomic approach. This endoxylanase candidate was amplified, cloned, heterologously expressed in Escherichia coli and purified. The recombinant enzyme was active at a broad range of temperatures (37–60 ºC) and pH values (4–10), with optimal activity at 50 ºC and pH 9. Moreover, its activity remained at more than 80% of its maximum at 50 °C for 8 h. In addition, Xyl10B was found to be stable in the presence of salt and several ions and chemical reagents frequently used in the industry. These characteristics make this enzyme an interesting candidate for pulp and paper bleaching industries, since this process requires enzymes without cellulase activity and resistant to high temperatures and alkaline pH (thermo-alkaliphilic enzymes). The products of xylan hydrolysis by Xyl10B (short xylooligosaccharides, xylose and xylobiose) could be suitable for application as prebiotics and in the production of bioethanol.Graphical

A Non-Enzymatic Electrochemical Biosensor for the Detection of Methylglyoxal in Human Blood Plasma

Methylglyoxal (MG) is one of the emerging biomarkers of diabetes, and the design and development of biosensors for it has gained a considerable benefit. At the same time, designing electrochemical MG biosensors with the working electrode modified with nanointerface and enzyme by drop casting has a number of disadvantages including fouling, nonuniform coating, and uncontrolled thickness. In this background, electrodeposited CS/MWCNTs on GCE for ultralow detection of MG has been proposed to minimise the limitations. The electrode was optimized for a range of scan rates and pH values in order to obtain the maximum response for a given concentration of MG. Cyclic voltammetry technique was employed to detect MG in human plasma. The reduction of MG to acetol at −0.745 V with a peak current of 291 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{A}$ </tex-math></inline-formula> when 10 nM of MG was added to the NaCl electrolyte. The linearity range was observed from 10 to 40 nM with a detection limit (LOD) of 25 pM, a quantification limit (LOQ) of 85 pM and a response time of less than 10 s. The performance of the sensor was tested in the presence of blood plasma samples.

Surface transformation thermodynamics of alkaline earth carbonates using first-principles calculations

Alkaline Earth (AE) carbonates are ubiquitous minerals with important roles in both industry and the environment. For example, CaCO3 helps regulate biogeochemical cycles and the amount of CO2 present in the atmosphere through cycles of dissolution and re-precipitation. Knowing the atomistic response of carbonates to changes in their chemical environment, such as by surface termination, composition, or pH, will allow for better controls of both naturally occurring processes and industrial applications. Here first-principles methods were used to investigate the initial stages of carbonate dissolution by comparing surface exchanges and ion release processes from the aragonite mineral phase. The focus was on computing the thermodynamics of CaCO3, SrCO3, and BaCO3 surface transformations and to link key features in surface structure to changes in the thermodynamics of ion release. The overall cycle of surface cation exchange, subsurface atom release, and subsequent surface healing was predicted to occur for a wide range of pH values. Surface bicarbonate reorganization, measured as a change in vertical height, dictated in part the thermodynamics of subsurface release, and it was shown that subsurface anion release was the most energetically costly part of the thermodynamic analyses. Moreover, these cycles resulted in thermodynamically stable defect structures that i) may be a better starting point for creating more accurate models of CO2 release and sequestration in aqueous environments, ii) could be used to guide future spectroscopic analyses, and iii) lead to improvements in technologies as diverse as nanomedicine, sensing, and water treatment.

Radon (222Rn) levels in thermal waters of the geothermally active Campi Flegrei volcanic caldera (Southern Italy): A framework study using a RAD7 radon detector

The present investigation provides measurements of radon (222Rn) concentration levels in 20 thermal waters at the Campi Flegrei volcanic caldera, an important geothermal system with hydrothermal manifestations in the Neapolitan area (Southern Italy). We used a RAD7® Radon-in-air detector equipped with Big Bottle RAD H2O and DRYSTIK accessories (Durridge Co. Inc.). Water samples with different chemical and/or physical conditions, not used as drink waters, are taken from continental thermal groundwaters, springs, lakes, pools and one submerged thermal spring. The waters are mostly chlorine to bicarbonate, except of a few sulphate types sampled at the hydrothermal discharge areas of Solfatara and Pisciarelli, central in the caldera. Water temperature and pH values range from 18.1 to 91.3 °C and from 2 to 8, respectively.Sampling and measurement of radon in groundwater are complicated by the high volatility of the gas; a method is here proposed. In some of the 20 sites double or triple samples were collected by using different volume polyethylene terephthalate (PET) bottles, diluting sample with blank water, and modifying flow of pumped wells. We suggest that dilution can be considered when water is i) not enough to fill in the PET, resulting in large head space in the sampler, ii) too hot determining damage of the PET or iii) too saline to clog the Big Bottle System.Dissolved radon concentrations vary from 0.1 ± 0.1 to 1146 ± 57 Bq/L with an average value of 152 Bq/L, using the CAPTURE program, the default RAD7 data acquisition program. Similar values in radon concentration are obtained using the method proposed in De Simone et al. (2015) ranging between 0.1 ± 5.8 and 1286 ± 98 Bq/L with an average value of 167 Bq/L. The hottest and most acidic sulphate waters refer to a small boiling pool at Pisciarelli hydrothermal discharge area and have nearly zero 222Rn content.222Rn concentrations from this study are mostly below the reference level of 1000 Bq/L recommended for human health protection by the European Commission and the most adopted in the scientific community (Catão et al., 2022). No correlation has been observed between temperature, pH, major anions and radon content values, nor between rock composition since it is almost homogeneous trachyte at the study sites. 222Rn levels therefore appear to reflect the local sedimentological, structural or hydrogeological conditions.The levels of 222Rn here presented are an important background for the scientific community that will intend to define the natural fluctuations of dissolved 222Rn in relation with seasons, environment, hydrogeology or volcanic dynamics at the geohazardous Campi Flegrei area.

A novel lytic phage potentially effective for phage therapy against Burkholderia pseudomallei in the tropics

BackgroundBurkholderia pseudomallei is a tropical pathogen that causes melioidosis. Its intrinsic drug-resistance is a leading cause of treatment failure, and the few available antibiotics require prolonged use to be effective. This study aimed to assess the clinical potential of B. pseudomallei phages isolated from Hainan, China.MethodsBurkholderia pseudomallei strain (HNBP001) was used as the isolation host, and phages were recovered from domestic environmental sources, which were submitted to the host range determination, lytic property assays, and stability tests. The best candidate was examined via the transmission electron microscope for classification. With its genome sequenced and analyzed, its protective efficacy against B. pseudomallei infection in A549 cells and Caenorhabditis elegans was evaluated, in which cell viability and survival rates were compared using the one-way ANOVA method and the log-rank test.ResultsA phage able to lyse 24/25 clinical isolates was recovered. It was classified in the Podoviridae family and was found to be amenable to propagation. Under the optimal multiplicity of infection (MOI) of 0.1, an eclipse period of around 20 min and a high titer (1012 PFU/ml) produced within 1 h were demonstrated. This phage was found stabile at a wide range of temperatures (24, 37, 40, 50, and 60 °C) and pH values (3–12). After being designated as vB_BpP_HN01, it was fully sequenced, and the 71,398 bp linear genome, containing 93 open reading frames and a tRNA-Asn, displayed a low sequence similarity with known viruses. Additionally, protective effects of applications of vB_BpP_HN01 (MOI = 0.1 and MOI = 1) alone or in combination with antibiotics were found to improve viability of infected cells (70.6 ± 6.8%, 85.8 ± 5.7%, 91.9 ± 1.8%, and 96.8 ± 1.8%, respectively). A significantly reduced mortality (10%) and a decreased pathogen load were demonstrated in infected C. elegans following the addition of this phage.ConclusionsAs the first B. pseudomallei phage was isolated in Hainan, China, phage vB_BpP_HN01 was characterized by promising lytic property, stability, and efficiency of bacterial elimination during the in vitro/vivo experiments. Therefore, we can conclude that it is a potential alternative agent for combating melioidosis.Graphical

Epistemic Uncertainties in the Assessment of Regional Soil Acidification

The increasing acidification of soil due to pollution and agricultural management practices is a growing problem worldwide, where food production is already under threat by climate change, more frequent droughts, and soil nutrient depletion. Soil acidification is quantified by pH measurements and is a primary metric for soil health. High soil acidity is a constraint on the production of grains and other crops because it decreases the bioavailability of important plant nutrients while increasing soil toxicity arising from an imbalance of essential soil elements. Field pH can be estimated by colour test kits which are very cost-effective and particularly suitable for developing countries where laboratory services are not available or fail to provide timely results. Because the pH test kit is based on visual colour matching between a colour card scale and a soil sample in solution, there are epistemic uncertainties, such as variability in expert opinion, differences in colour vision, measurement error, instrumentation, and changes in daylight spectral content. In this study, expert human observers were compared in experiments conducted using a standard pH test kit under a range of environmental conditions. A significant difference in uncertainty in colour discrimination was evident between male and female experts, whereas changes in daylight conditions had lower impact on the variance of pH estimates. In a group of subject matter experts, the male standard error (0.35 pH) was 57% higher on average over the range of pH values (pH = 4 → 10) compared to females (0.22 pH). This error was largest (70%) in the low pH 4 to 6.5 range, which is a critical range for successful amelioration of soil acidification. The results suggest that historical database measurements may have hitherto unrecognised uncertainties that affect confidence intervals for experimental data that in turn will have an impact on predictive models and policy development.

Phosphorus release from hydrothermally carbonized digested sewage sludge using organic acids

Hydrothermal carbonization (HTC) is a treatment technique with great potential for sanitizing digested sewage sludge (SS) and converting it into valuable products. In particular, phosphorus (P) recovery from hydrothermally carbonized SS has attracted special attention in recent years. This work aims to examine the leaching efficiency of P and the consequent release of metals and heavy metals from SS hydrochars (at 180, 215 and 250 °C) using organic acids (oxalate and citrate) over a range of pH values (0–4) and extraction times (5 min-24 h). Both organic acids triggered P extraction efficiencies exceeding 75 % at the lowest pH, but only oxalate reached a nearly complete P release from hydrochars at pH > 0 and for all carbonization temperatures. Low HTC temperature (180 °C) and short extraction time (5 min) were the optimal conditions treatment for P recovery when reacted in oxalate solutions of maximal pH buffering capacity (pH = 1.4). However, oxalate leaching also transferred metals/heavy metals into the P-leachate, with the exception of Ca being retained in the solid residue from HTC as Ca-oxalate precipitate. Different characterization methods confirmed the presence of this precipitate, and provided information about the surface and morphological changes of the SS hydrochars following acid treatment. The results suggest that HTC not only a promising technique to sanitize and reduce the volume of SS, but also an efficient means for P recovery using oxalic acid, thus contributing to the circular economy of P.

The influence of phosphorus application and varying soil pH on soil and herbage properties across a range of grassland soils with impeded drainage

AbstractOn soils dominated by high proportions of clay and organic matter, soil acidity and poor nutrient use efficiency have a major impact on output potential. Due to the inherent chemical properties of these soils, reducing soil acidity and the prevalence of undesirable metallic cations poses challenges. As a result, these soils have a large capacity for phosphorus (P) fixation, therefore reducing plant P availability. Limestone (CaCO3or MgCO3) is applied to agricultural soils to counteract soil acidity and reduce P fixation. The current study investigates the effects of four contrasting annual P application rates (0, 50, 100, 150 kg P/ha); split (50:50) between spring and summer, across soils with a range of soil pH values from a previous liming trial. The effect of soil pH ranges and P treatment rates on seasonal herbage growth and herbage P concentration was investigated over three years. Soil nutrient status was also investigated. Soil pH had a significant impact on the rate of mineralization and soil P concentration across each site. A soil pH of 6.2 caused a 1.8 mg/l increase in soil test P. An annual P application was necessary to maintain sufficient herbage P concentration for animal dietary requirements (0.35% DM), however there was no effect of P application or liming rate on herbage productivity across the three sites as all sites possessed sufficient soil P reserves. The current experiment has shown that despite optimal soil fertility status, ensuring sufficient plant available P is a problem on these particular soils.

Soil and Vegetation Development on Coal-Waste Dump in Southern Poland.

As an anthropogenic element of urban landscapes, coal heaps undergo changes due to both natural and anthropogenic factors. The aim of this study was to determine the common development of soil under the influence of vegetation succession against a background of environmental conditions. Vegetation changes and soil properties were analysed along a transect passing through a heap representing a particular succession stage. It was found that changes in the development of vegetation were closely related to the stages of coal-waste disposal, where the initial, transitional, and terminal stages were distinguished. The mean range of pH (H2O) values in the profiles was 6.75 ± 0.21 (profile 1), 7.2 ± 0.31 (profile 2), 6.3 ± 1.22 (profile 3), and 5.38 ± 0.42 (profile 4). The organic carbon (OC) content in all samples was high, ranging from 9.6% to 41.6%. The highest content of total nitrogen (Nt) was found (1.132%) in the algal crust and sub-horizon of the organic horizon (Olfh-0.751%) and humus (A-0.884) horizon in profile 3 under the initial forest. Notable contents of available elements were found in the algal shell for P (1588 mg∙kg−1) and Mg (670 mg∙kg−1). Soil organic matter content was mainly dominated by n-alkanes (n-C11-n-C34) and alkanoic acids (C5–C20). Phytene and Phytadiene were typical for the algal crust on the initial pedigree. The initiation of succession was determined by the variation in grain size of the waste dumped on the heap and the variation in relief and associated habitat mosaic. Algal crusts forming on clay–dust mineral and organic material accumulating in the depressions of the site and at the foot of the heap can be regarded as the focus of pedogenesis.

Development of an automated millifluidic platform and data-analysis pipeline for rapid electrochemical corrosion measurements: A pH study on Zn-Ni

We describe the development of a millifluidic based scanning droplet cell platform for rapid and automated corrosion. This system allows for measurement of corrosion properties (e.g., open circuit potential, corrosion current through Tafel and linear polarization resistance measurements, and cyclic voltammograms) on a localized section of a planar sample. Our system is highly automated and flexible, allowing for scripted changing and mixing of solutions and point-to-point motion on the sample. We have also created an automated data analysis pipeline. Here we demonstrate this tool by corroding a plate of electroplated Zn85Ni15 alloy over a range of pH values and correlate our results with XPS measurements and literature.

Development of Millettia speciosa champ polysaccharide conjugate stabilized oil-in-water emulsion for oral delivery of β-carotene: Protection effect and in vitro digestion fate

In this study, a natural antioxidant emulsifier, Millettia speciosa Champ polysaccharide conjugates (MSC-PC), was used for fabricating oil-in-water emulsion, and the influences of MSC-PC on β-carotene stability and bioaccessibility were studied. Results suggested that MSC-PC stabilized emulsion exhibited excellent resistance to a wide range of salt levels (0–500 mM of Na+), thermal treatments (50–90 °C) and pH values (3.0–11.0). MSC-PC also exhibited an outstanding inhibition capacity on lipid oxidation. Besides, MSC-PC stabilized emulsion had a better protective effect on β-carotene than other systems. Interestingly, in spite of similar lipolysis extent, β-carotene bioaccessibility in MSC-PC fabricated emulsion (14.75 %) was markedly higher than that in commercial Tween 80 fabricated emulsion (10.08 %), likely due to the steric-hindrance effect and antioxidant ability of MSC-PC, building interfacial layers that prevented β-carotene from degradation. This work supplied a deep insight into elucidating the mechanisms of emulsifying performance and β-carotene protection effect of MSC-PC fabricated emulsion.

Nanomaterials: An Efficient Support to Immobilize Microbial α–Amylases for Improved Starch Hydrolysis

AbstractMicrobial enzymes have contributed significantly to the development of biotech based industries over the recent past. Importantly, the microbial α‐amylases share a major market along with proteases. Starch gets hydrolyzed to dextrin, maltotetroses, maltotrioses, maltose, and glucose in trace amount using amylases. To be suitable commercially, the amylase should be stable at higher temperatures and a wide range of pH values. Moreover, it should also exhibit resistance against a range of chelators, surfactants, and denaturants. It is quite strenuous to isolate an amylase harboring all the required qualities. Therefore, various strategies have been employed to achieve the required attributes. In the present mini‐review, amylase immobilization on conventional matrices as well as on different types of nanomaterials has been discussed with a special emphasis on improvement in the stability and reusability. The stability of the nanomaterials against various physical, chemical, and biological stress is a key factor to be explored commercially. The mini‐review includes mainly magnetite, non‐magnetite, and hybrid (organic–inorganic) nanomaterials. Conclusively, it is anticipated that the advanced strategies would help to overcome the technical barriers in the industrial sectors for better continuous applications of microbial amylases.

Cynara cardunculus as a potential source of milk coagulating protease: Effects on physical properties of cow's milk.

In the present research study, Cynara cardunculus (wild cardoon) flowers were blended and extracted using different types of buffers (phosphate buffer; citrate buffer and distilled water) for different maceration times. The most reliable, quick and efficient buffer was found to be phosphate (pH=6.5) with a 6-h maceration time, which was used throughout this study. C. cardunculus extract (CE) was found to have high clotting and proteolytic activities. The extracted enzyme was found to be very stable against a wide range of pH values as well as of temperature. The formation of milk gels prepared in the presence of CE with different types of milk was evaluated using dynamic rheology and Turbiscan. The evolution of both elastic (G') and viscous (G″) moduli was monitored with time. The values of the whole milk enriched with milk powder gels were higher. Coagulum stability was evaluated using Turbiscan. The textural properties and the curd-firming rate of coagulum were also determined. In conclusion, the prepared CE could be an efficient milk-clotting agent in the production of dairy products.

Prediction of pH Value of Aqueous Acidic and Basic Deep Eutectic Solvent Using COSMO-RS σ Profiles' Molecular Descriptors.

The aim of this work was to develop a simple and easy-to-apply model to predict the pH values of deep eutectic solvents (DESs) over a wide range of pH values that can be used in daily work. For this purpose, the pH values of 38 different DESs were measured (ranging from 0.36 to 9.31) and mathematically interpreted. To develop mathematical models, DESs were first numerically described using σ profiles generated with the COSMOtherm software. After the DESs’ description, the following models were used: (i) multiple linear regression (MLR), (ii) piecewise linear regression (PLR), and (iii) artificial neural networks (ANNs) to link the experimental values with the descriptors. Both PLR and ANN were found to be applicable to predict the pH values of DESs with a very high goodness of fit (R2independent validation > 0.8600). Due to the good mathematical correlation of the experimental and predicted values, the σ profile generated with COSMOtherm could be used as a DES molecular descriptor for the prediction of their pH values.

Determination of Glucose by the Catalysis of Luminol Chemiluminescence Using One-Step Synthesized Platinum/Silver Nanoparticles as a Peroxidase Mimetic

Bimetallic Pt/Ag nanoparticles (Pt/Ag NPs) were synthesized using 3-hydroxyphenyl-boronic acid as the reducing and stabilizing agent by a simple, one-step hydrothermal method. The bimetallic Pt/Ag NPs were demonstrated to possess intrinsic peroxidase mimetic catalytic activity for the luminol/H2O2 reaction to generate chemiluminescence (CL). The catalytic properties of the bimetallic Pt/Ag NPs were thoroughly investigated. The results showed that the combination of Pt and Ag greatly enhanced the chemiluminescence which is attributed to their synergy. Moreover, the prepared bimetallic Pt/Ag NPs exhibited superior peroxidase mimetic activity to horseradish peroxidase and were stable under a wide range of pH values and temperatures. Using the bimetallic Pt/Ag NPs as the catalyst, a novel chemiluminescence sensor was developed for the determination of glucose with a linear range from 1 to 500 µM and a detection limit of 0.35 µM. The developed method was successfully employed to determine glucose in human serum with satisfactory results. Bimetallic Pt/Ag NPs with peroxidase mimetic catalytic activity have promising applications for determination of glucose in clinical samples.

Iodine stability as a function of pH and its implications for simultaneous multi-element ICP-MS analysis of marine carbonates for paleoenvironmental reconstructions

Analyses of marine carbonates using solution-based ICP-MS typically occur in dilute acid, as alkaline solutions can cause CaCO3 and metal-oxide/oxyhydroxide precipitation. Measurement of iodine to calcium (I/Ca) ratios in marine carbonates—most often in the calcite shells, or tests, of foraminifera—are challenging to pair with those of pH-sensitive metals, as iodine is unstable in acidic solution and will volatilize in the presence of light and air. As a result, I/Ca ratios are routinely analyzed in basic solution, requiring additional sample material and analytical time. Leveraging the equilibrium relationships between thermodynamically stable, inorganic iodine species across a wide range of electrochemical potential (pE) and pH values, we determine which species are present in low-temperature, aqueous solutions characteristic of marine carbonate analysis on quadrupole ICP-MS, and suggest appropriate solution pH(s) for iodine measurement. Our results demonstrate that iodine is capable of volatilization at all pH values <10.5, though it is most volatile in the pH range of 0–1. Furthermore, at pH values above 10.5, solutions are susceptible to contamination from gas-phase molecular iodine, I2.Employing this knowledge of iodine speciation, we establish a high precision method for the solution-based analysis of iodine alongside twelve other elements (Li, Na, Mg, Al, Mn, Fe, Zn, Sr, Cd, Ba, U, and Ca) on a collision-reaction cell equipped quadrupole ICP-MS in the acidic pH range. Using a 9:1 volume/volume mixture of 0.5% tetramethylammonium hydroxide (TMAH) and 2% nitric acid (HNO3), we can reproducibly analyze iodine concentrations in a complex carbonate (calcite and aragonite) matrix alongside other elemental ratios used in paleo-environmental reconstructions. This mixture of dilute acid and base maintains acidic pH (1.5 ± 0.14), avoiding the precipitation of pH-sensitive metal oxides/oxyhydroxides and CaCO3 while minimizing iodine volatilization. We demonstrate that iodine concentrations measured using ICP-MS are only effectively stabilized in the pH range of 1.5–10.5 and recommend pH-matching sample and standard solutions. This method allows the extraction of considerably more directly comparable paleo-environmental information from the analysis of a single foraminiferal sample.

Purification and Identification of a Novel Angiotensin Converting Enzyme Inhibitory Peptide from the Enzymatic Hydrolysate of Lepidotrigla microptera.

In this study, Lepidotrigla microptera were hydrolyzed with four different proteolytic enzymes (Papain, neutrase, flavourzyme, and alcalase), and their distribution of molecular weights and ACE-inhibitory activity were tested. The alcalase hydrolysates showed the maximum ACE-inhibitory activity. A novel ACE-inhibitory peptide was isolated and purified from Lepidotrigla microptera protein hydrolysate (LMPH) using ultrafiltration, gel filtration chromatography, and preparative high performance liquid chromatography (prep-HPLC). The amino acid sequence of the purified peptide was identified as Phe-Leu-Thr-Ala-Gly-Leu-Leu-Asp (DLTAGLLE), and the IC50 value was 0.13 mg/mL. The ACE-inhibitory activity of DLTAGLLE was stable across a range of temperatures (<100 °C) and pH values (3.0–11.0) and retained after gastrointestinal digestion. DLTAGLLE was further identified as a noncompetitive inhibitor by Lineweaver–Burk plot. The molecular docking simulation showed that DLTAGLLE showed a high binding affinity with ACE sites by seven short hydrogen bonds. As the first reported antihypertensive peptide extracted from alcalase hydrolysate of Lepidotrigla microptera, DLTAGLLE has the potential to develop functional food or novel ACE-inhibitor drugs.

Parametric Study of Methyl Orange Removal Using Metal–Organic Frameworks Based on Factorial Experimental Design Analysis

Wastewater treatment plants (WWTPs) are one of the most energy-intensive industries. Every stage of wastewater treatment consumes energy, which is the primary contributor to WWTP costs. Adsorbents and process optimization are critical for energy savings. The removal of dyes from industrial wastewater by adsorption using commercially available adsorbents is inefficient. Metal–organic frameworks (MOFs) have outstanding properties that can improve separation performance over current commercial adsorbents, and thus, these materials represent a milestone in improving dye removal in water treatment methods. In this work, three types of metal–organic frameworks (Fe-BTC, Cu-BTC, and ZIF-8) have been investigated as prospective adsorbents for methyl orange removal from water in batch setups. The results showed that at 15 mg/L MO initial concentration and 100 mg dosage, Fe-BTC had the highest removal efficiency of 91%, followed by ZIF-8 (63%), and finally Cu-BTC (35%), which exhibited structural damage due to its instability in water. Fe-BTC maintained consistent adsorption capacity over a wide range of pH values. Furthermore, a 23 full factorial design analysis was implemented to evaluate the conditions for maximum MO-removal efficiency. The main effects, interaction effects, analysis of variance (ANOVA), and the Pareto chart were reported. The statistical analysis demonstrated that the MOF type was the most significant factor, followed by dosage and initial concentration. The analysis indicated that the type of MOF and dosage had a positive effect on the removal efficiency, while the initial concentration had a negative effect. The two-way and three-way interactions were also found to be significant.