Range Of pH Values Research Articles

Expression optimization and characterization of a novel amylopullulanase from the thermophilic Cohnella sp. A01

Amylopullulanase (EC. 3.2.1.41/1) is an enzyme that hydrolyzes starch and pullulan, capable of breaking (4 → 1)-α and (6 → 1)-α bonds in starch. Here, the Amy1136 gene (2166 base pairs) from the thermophilic bacterium Cohnella sp. A01 was cloned into the expression vector pET-26b(+) and expressed in Escherichia coli BL21. The enzyme was purified using heat shock at 90 °C for 15 min. The expression optimization of Amy1136 was performed using Plackett–Burman and Box–Behnken design as follows: temperature of 26.7 °C, rotational speed of 180 rpm, and bacterial population of 1.25. The Amy1136 displayed the highest activity at a temperature of 50 °C (on pullulan) and a pH of 8.0 (on starch) and, also exhibited stability at high temperatures (90 °C) and over a range of pH values. Ag+ significantly increased enzyme activity, while Co2+ completely inhibited amylase activity. The enzyme was found to be calcium-independent. The kinetic parameters Km, Vmax, kcat, and kcat/Km for amylase activity were 2.4 mg/mL, 38.650 μmol min−1 mg−1, 38.1129 S−1, and 0.09269 S−1mg mL−1, respectively, and for pullulanase activity were 173.1 mg/mL, 59.337 μmol min−1 mg−1, 1.586 S−1, and 1.78338 S−1mg mL−1, respectively. The thermodynamic parameters Kin, t1/2, Ea#, ΔH#, ΔG# and ΔS# were calculated equal to 0.20 × 10−2 (m−1), 462.09 (min), 16.87 (kJ/mol), 14.18 (kJ/mol), 47.34 (kJ/mol) and 102.60 (Jmol K−1), respectively. The stability of Amy1136 under high temperature, acidic and alkaline pH, surfactants, organic solvents, and calcium independence, suggests its suitability for industrial applications.

Regulating the dominant reactive oxygen species from Fe(IV)-oxo to 1O2 by deprotonation of Fe(IV)-oxo in electro-Fe(II)/periodate system

The ferrous species (Fe(II))-periodate (PI) system employs efficient decontamination by generating ferryl species (Fe(IV)-oxo) under acidic pH conditions. However, the mechanisms by which the Fe(II)/PI system operates across a broad pH range remain elusive. In light of the rapid oxidation and consumption of Fe(II) at neutral pH, we developed an electro-Fe(II) system utilizing an iron plate anode to activate PI (E(Fe/C)/PI). Efficient sulfamethoxazole (SMX) degradation was achieved under the E(Fe/C)/PI system across a range of pH values. Quenching and chemical probe experiments revealed a transition from Fe(IV)-oxo to singlet oxygen (1O2) as the predominant reactive species from acidic to near-neutral pH, respectively. Density functional theory (DFT) calculations indicated that the differences in one-electron transfer capacity and hydrolysis pathways for various protonated Fe(IV)-oxo species underlie the variations in catalytic mechanisms. This study not only enhances the efficiency of the Fe(II)/PI system but also provides a comprehensive understanding of the activation mechanisms at different pH levels.

Preparation and Characterization of Responsive Cellulose-Based Gel Microspheres for Enhanced Oil Recovery.

As an important means to enhance oil recovery, ternary composite flooding (ASP flooding for short) technology has achieved remarkable results in Daqing Oilfield. Alkalis, surfactants and polymers are mixed in specific proportions and injected into the reservoir to give full play to the synergistic effect of each component, which can effectively enhance the fluidity of crude oil and greatly improve the oil recovery. At present, the technology for further improving oil recovery after ternary composite flooding is not mature and belongs to the stage of technical exploration. The presence of alkaline substances significantly alters the reservoir's physical properties and causes considerable corrosion to the equipment used in its development. This is detrimental to both the environment and production. Therefore, it is necessary to develop green displacement control agents. In the reservoir environment post-ASP flooding, 2-(methylamino)ethyl methacrylate and glycidyl methacrylate were chosen as monomers to synthesize a polymer responsive to alkali, and then grafted with cellulose nanocrystals to form microspheres of alkali-resistant swelling hydrogel. Cellulose nanocrystals (CNCs) modified with functional groups and other materials were utilized to fabricate hydrogel microspheres. The product's structure was characterized and validated using Fourier transform infrared spectroscopy and X-ray diffraction. The infrared spectrum revealed characteristic absorption peaks of CNCs at 1165 cm-1, 1577 cm-1, 1746 cm-1, and 3342 cm-1. The diffraction spectrum corroborated the findings of the infrared analysis, indicating that the functional modification occurred on the CNC surface. After evaluating the swelling and erosion resistance of the hydrogel microspheres under various alkaline conditions, the optimal particle size for compatibility with the target reservoir was determined to be 6 μm. The potential of cellulose-based gel microspheres to enhance oil recovery was assessed through the evaluation of Zeta potential and laboratory physical simulations of oil displacement. The study revealed that the absolute value of the Zeta potential for gel microspheres exceeds 30 in an alkaline environment with pH values ranging from 7 to 14, exhibiting a phenomenon where stronger alkalinity correlates with a greater absolute value of Zeta potential. The dispersion stability spans from good to excellent. The laboratory oil displacement simulation experiment was conducted using a cellulose-based gel microsphere system following weak alkali ASP flooding within the pH value range from 7 to 10. The experimental interventions yielded recovery rates of 2.98%, 3.20%, 3.31%, and 3.38%, respectively. The study indicates that cellulose-based gel microspheres exhibit good adaptability in alkaline reservoirs. This research offers a theoretical foundation and experimental approaches to enhance oil recovery techniques post-ASP flooding.

Enhanced pH sensing with cholesteric liquid crystal-infused sodium alginate actuators

The present work developed a novel type of soft actuator capable of pH sensing, named CLC-SAA (Cholesteric Liquid Crystal-Infused Sodium Alginate Actuator). This actuator is created by combining sodium alginate hydrogel with cholesteric liquid crystal via an evaporation method. Our study validates the actuation mechanism by observing shifts in the vibrational stretching of carboxylic group bonds through FTIR spectroscopic investigations. Leveraging the weak acidic nature of carboxylic acid in sodium alginate hydrogel, this actuator offers distinct advantages. The CLC-SAA exhibits remarkably rapid bending responses, with fast responses observed of the order of 4 sec to 0.4 sec and bending angles as low as 3° to as high as 18°. This responsiveness is consistent across a wide range of pH values, making it highly adaptable and valuable for applications in medical, chemical, and bio-robotics fields. Such actuation holds significant promise for various applications due to its adaptability and wide-ranging capabilities.

The Faradaic-Induced hybrid capacitive engine enables high-performance selective defluorination via capacitive deionization

Fluoride (F-) contamination has become a pressing environmental concern owing to its extensive origins and severe toxicity. Capacitive deionization (CDI) emerges as a promising technique for efficient defluorination, with the development of electrode materials being pivotal to its efficiency. Herein, we present a novel design of Sb-decorated N-rich carbon composites (SNTPCs) for the formation of a hybrid capacitive engine that integrates Faradaic-induced pseudocapacitance and electrical double layer capacitance, enabling efficient F- electrosorption. This approach features a distinctive N-rich carbonaceous laminar framework that not only guarantees rapid ion diffusion and electron transfer but also provides a dense electrical double layer for F- storage. The Sb sites are electrically stimulated to release the intrinsic affinity with F-, forming the Faradaic Sb-F bonds. The SNTPC2 electrode exhibits the exceptional saturation removal capability and dynamic electrosorption capacity for defluorination, reaching 178.58 and 34.77 mg F/g at 1.2 V respectively, which exceeds most reported F- capture electrodes. It also demonstrates excellent selectivity towards F- in complex conditions and exhibits effectiveness across a wide range of pH values. Additionally, the utilized electrode performs outstanding regeneration performance after 20 consecutive cycles. This study provides innovative perspectives for the effective elimination of fluoride pollution in aquatic environments.

Influence of titanium surface roughness on a nanoscale on the zeta potential and platelet adhesion.

Thromboembolic complications still arise on blood contacting surfaces. Surface charge and topography influence the subsequent deposition of proteins and platelets, potentially leading to thrombi. Research showed a correlation of surface charge and nanoscale roughness, and a negative surface charge as well as a smooth surface finish are associated with lower thrombogenicity. The aim of this study was to compare the platelet adhesion on titanium with different nanoscale roughnesses and to examine if those roughness variations caused a change in surface charge. Titanium samples were polished and roughened to four different nanoscale roughness levels. Platelet adhesion (covered surface area (CSA), N = 8) was tested in flow chambers with human whole blood using fluorescence imaging. ζ-potential was measured over a broad range of pH-values and interpolated to obtain the ζ-potential for pHBlood (7.4). Platelet adhesion tests were evaluated in terms of p-values and the Wilcoxon test effect size and the trend of the ζ-potential at pHBlood and the CSA was compared. Ra-values ranged between 35 (polished) and 156 nm. Regarding platelet adhesion, the polished sample showed the lowest mean CSA with a medium or strong effect size compared to the roughened samples. The interpolated ζ-potentials for pHBlood follow a similar trend as the CSA, with the lowest ζ-potential measured for the polished surface. These findings suggest that the decreasing ζ-potential due to lower nanoscale roughness might be an additional explanation for the improved hemocompatibility besides the smoother topography.

A new UiO-66-NH2 MOF-based nano-immobilized DFR enzyme as a biocatalyst for the synthesis of anthocyanidins

Anthocyanidins and anthocyanins are one subclass of flavonoids in plants with diverse biological functions and have health-promoting effects. Dihydroflavonol 4-reductase (DFR) is one of the important enzymes involved in the biosynthesis of anthocyanidins and other flavonoids. Here, a new MOF-based nano-immobilized DFR enzyme acting as a nano-biocatalyst for the production of anthocyanidins in vitro was designed. We prepared UiO-66-NH2 MOF nano-carrier and recombinant DFR enzyme from genetic engineering. DFR@UiO-66-NH2 nano-immobilized enzyme was constructed based on covalent bonding under the optimum immobilization conditions of the enzyme/carrier ratio of 250 mg/g, 37 °C, pH 6.5 and fixation time of 10 min. DFR@UiO-66-NH2 was characterized and its catalytic function for the synthesis of anthocyanidins in vitro was testified using UPLC-QQQ-MS analysis. Compared with free DFR enzyme, the enzymatic reaction catalyzed by DFR@UiO-66-NH2 was more easily for manipulation in a wide range of reaction temperatures and pH values. DFR@UiO-66-NH2 had better thermal stability, enhanced adaptability, longer-term storage, outstanding tolerances to the influences of several organic reagents and Zn2+, Cu2+ and Fe2+ ions, and relatively good reusability. This work developed a new MOF-based nano-immobilized biocatalyst that had a good prospect of application in the green synthesis of anthocyanins in the future.

Enhancing the environmental and economic sustainability of heterotrophic microalgae cultivation: Kinetic modelling and screening of alternative carbon sources

Heterotrophic microalgae cultivation has been suggested to reduce conventional photo-autotrophic microalgal biomass production costs. In heterotrophic cultivation, the most relevant operational costs are constituted by the supply of pure substrates used as carbon source (e.g., glucose), and the high energy request for culture aeration. In addition, suboptimal conditions of temperature and pH reduce the algal productivity, further increasing production costs. In this work, an attempt was made to define more sustainable and cost-effective strategies for the heterotrophic cultivation of Chlorellaceae and Scenedesmaceae. Several by-products from a local confectionery industry were thus screened as alternative carbon sources. Manufacturing residues from peppermint and liquorice candies production allowed to achieve comparable maximum growth rates (1.44 d-1), biomass yields (0.33 g COD·g COD-1) and biomass productivities (370 mg COD·L-1·d-1) as those achieved using glucose. A preliminary economic evaluation showed that the operational costs could be lowered of up to 85.6% by substituting glucose with the selected industrial by-products. As for fermentation conditions, high growth rates could be maintained at relatively low dissolved oxygen (DO) concentrations, and in a large range of temperature and pH values. In addition, optimal temperatures (37.0 – 37.2°C), pH values (6.8 – 7.4), and DO concentrations (> 0.5 – 1 mg O2·L-1) were identified. On the overall, the study demonstrated the possibility of achieving the reduction of operational costs for heterotrophic microalgae cultivation, while implementing circular economy principles in the framework of resource recovery during the bioremediation of organic waste.

Hydrogen generation from catalytic hydrolysis of ammonia borane with Co-Cu-B/g-C3N4/NF catalyst

In this study, different double-supported Co-Cu-B/g-C3N4/Ni foam (NF=Ni foam) catalysts were synthesized by chemical deposition method in a certain pH value range (pH value between 10.5 and 12.0). Their catalytic performances of hydrolyzing ammonia borane (NH3BH3) hydrolysis were investigated to produce hydrogen at 298 K. Because of the adding of g-C3N4 in the plating solution, the obtained sample had certain photocatalytic activity when the visible light was introduced the hydrolysis experiment. The results displayed that the as-prepared Co-Cu-B/g-C3N4/NF catalyst at pH = 10.5 exhibited an improved catalytic effect for NH3BH3 hydrolysis under visible light irradiation. The corresponding hydrogen generation rate reached 8893 mol·min−1·g−1, and the activation energy was 41.8 kJ·mol−1. The catalytic performance of Co-Cu-B/g-C3N4/NF catalysts prepared by this method is better than that of as-obtained mono-metal Co-B/g-C3N4/NF catalyst. More importantly, its activity has exceeded many single-carrier cobalt-based catalysts reported so far, and even some single-support precious metal catalysts for NH3BH3 hydrolysis. It indicated that the strategy of double carriers and introduction of light contributed to the improvement in catalytic activity for the non-noble metal-based catalysts during NH3BH3 hydrolysis.

Development of a novel ratiometric fluorescent probe for real-time monitoring of acidic pH and its applications in food samples and biosystem

In this research, a high-efficiency ratiometric fluorescent probe TZTF for sensitive detecting the fluctuations of acidic pH was synthesized. The fluorescent color changed from bright blue to orange in the pH values range from 8.0 to 1.0 with the pKa value of 5.41. Meanwhile, the probe demonstrated excellent selectivity, good anti-interference ability, prominent reversibility, outstanding photostability, and low cytotoxicity. The detection mechanism of TZTF towards acidic pH was verified through 1H NMR analysis and DFT calculation. Additionally, probe TZTF was also applied to evaluate the freshness of meat samples, as the pH value of meat samples may decrease if they are not stored properly, and the subsequent acid-catalyzed denaturation of proteins may pose a threat to human health through the food chain. More importantly, fluorescence imaging experiments confirmed that TZTF is appropriate for real-time tracking of pH variations in living cells and living zebrafish.

A colloidal model for the equilibrium assembly and liquid-liquid phase separation of the reflectin A1 protein

Reflectin is an intrinsically disordered protein known for its ability to modulate the biophotonic camouflage of cephalopods based on its assembly-induced osmotic properties. Its reversible self-assembly into discrete, size-controlled clusters and condensed droplets are known to depend sensitively on the net protein charge, making reflectin stimuli-responsive to pH, phosphorylation, and electric fields. Despite considerable efforts to characterize this behavior, the detailed physical mechanisms of reflectin’s assembly are not yet fully understood. Here, we pursue a coarse-grained molecular understanding of reflectin assembly using a combination of experiments and simulations. We hypothesize that reflectin assembly and phase behavior can be explained from a remarkably simple colloidal model whereby individual protein monomers effectively interact via a short-range attractive and long-range repulsive (SA-LR) pair potential. We parameterize a coarse-grained SA-LR interaction potential for reflectin A1 from small-angle x-ray scattering measurements, and then extend it to a range of pH values using Gouy-Chapman theory to model monomer-monomer electrostatic interactions. The pH-dependent SA-LR interaction is then used in molecular dynamics simulations of reflectin assembly, which successfully capture a number of qualitative features of reflectin, including pH-dependent formation of discrete-sized nanoclusters and liquid-liquid phase separation at high pH, resulting in a putative phase diagram for reflectin. Importantly, we find that at low pH size-controlled reflectin clusters are equilibrium assemblies, which dynamically exchange protein monomers to maintain an equilibrium size distribution. These findings provide a mechanistic understanding of the equilibrium assembly of reflectin, and suggest that colloidal-scale models capture key driving forces and interactions to explain thermodynamic aspects of native reflectin behavior. Furthermore, the success of SA-LR interactions presented in this study demonstrates the potential of a colloidal interpretation of interactions and phenomena in a range of intrinsically disordered proteins.

Avian Orthoreoviruses: A Systematic Review of Their Distribution, Dissemination Patterns, and Genotypic Clustering.

Avian orthoreviruses have become a global challenge to the poultry industry, causing significant economic impacts on commercial poultry. Avian reoviruses (ARVs) are resistant to heat, proteolytic enzymes, a wide range of pH values, and disinfectants, so keeping chicken farms free of ARV infections is difficult. This review focuses on the global prevalence of ARVs and associated clinical signs and symptoms. The most common signs and symptoms include tenosynovitis/arthritis, malabsorption syndrome, runting-stunting syndrome, and respiratory diseases. Moreover, this review also focused on the characterization of ARVs in genotypic clusters (I-VI) and their relation to tissue tropism or viral distribution. The prevailing strains of ARV in Africa belong to all genotypic clusters (GCs) except for GC VI, whereas all GCs are present in Asia and the Americas. In addition, all ARV strains are associated with or belong to GC I-VI in Europe. Moreover, in Oceania, only GC V and VI are prevalent. This review also showed that, regardless of the genotypic cluster, tenosynovitis/arthritis was the predominant clinical manifestation, indicating its universal occurrence across all clusters. Globally, most avian reovirus infections can be prevented by vaccination against four major strains: S1133, 1733, 2408, and 2177. Nevertheless, these vaccines may not a provide sufficient defense against field isolates. Due to the increase in the number of ARV variants, classical vaccine approaches are being developed depending on the degree of antigenic similarity between the vaccine and field strains, which determines how successful the vaccination will be. Moreover, there is a need to look more closely at the antigenic and pathogenic properties of reported ARV strains. The information acquired will aid in the selection of more effective vaccine strains in combination with biosecurity and farm management methods to prevent ARV infections.

Applications of bacteriophage in combination with nisin for controlling multidrug-resistant Bacillus cereus in broth and various food matrices

This study focused on the isolation and characterization of bacteriophages with specific activity against toxin-producing and multidrug-resistant strains of Bacillus cereus sensu stricto (B. cereus s. s.). Ten different samples yielded six bacteriophages by utilizing the double-layer agar technique. The most promising phage, vB_BceS-M2, was selected based on its broad host range and robust lytic activity against various B. cereus s. s. strains. The phage vB_BceS-M2 had a circular double-stranded DNA genome of 56,482 bp. This phage exhibited stability over a wide range of temperatures and pH values, which is crucial for its potential application in food matrices. The combined effect of phage vB_BceS-M2 and nisin, a widely used antimicrobial peptide, was investigated to enhance antimicrobial efficacy against B. cereus in food. The results suggested that nisin showed synergy and combined effect with the phage, potentially overcoming the growth of phage-resistant bacteria in the broth. Furthermore, practical applications were conducted in various liquid and solid food matrices, including whole and skimmed milk, boiled rice, cheese, and frozen meatballs, both at 4 and 25 °C. Phage vB_BceS-M2, either alone or in combination with nisin, reduced the growth rate of B. cereus in foods other than whole milk. The combination of bacteriophage and nisin showed promise for the development of effective antimicrobial interventions to counteract toxigenic and antibiotic-resistant B. cereus in food.

Natural Polyelectrolyte Hydrogels with Two Types of Cross-Links with Different Energy

For the first time, gels of a polymer cross-linked by two types of ionic cross-links of different energies, namely trivalent chromium (III) ions and divalent iron (II) ions, were prepared. The negatively charged polysaccharide xanthan, a polyelectrolyte of natural origin, was used as a polymer. A study of xanthan gels cross-linked with each cross-linker separately was carried out to identify the optimal concentrations of each cross-linker for the production of a double cross-linked gel. The mechanical properties of hydrogels under oscillatory shear deformations were then studied. It was demonstrated that the simultaneous use of two cross-linkers resulted in a synergistic increase in the elastic modulus (plateau storage modulus) compared to gels cross-linked with each cross-linker separately. For a gel with two types of cross-links, the elastic modulus was 16 Pa. In contrast, for gels cross-linked with either chromium (III) cations or iron (II) cations, the elastic modulus was approximately 0.6 and 0.5 Pa, respectively. The strong effect can be attributed to the different nature of cross-linking between xanthan macromolecules and chromium (III) and iron (II) cations, as well as the different strength of the cross-links formed. The optimal range of pH values was determined in which a synergistic increase in the elastic modulus of gels with two types of cross-links was observed compared to the corresponding gels cross-linked with each cross-linker separately. Consequently, the concurrent utilisation of two cross-linking agents that generate cross-links with disparate energy levels represents an efficacious strategy to improve the tensile strength of polymer hydrogels.

Improving azo dyes degradation by CoFe2O4-activated peroxymonosulfate: Performance, degradation mechanism, and ecotoxicity assessment

Development of an effective catalyst is essential to eliminate the risks to ecological environment and human health caused by the accumulation of azo dyes in environmental water. Herein, the cobalt ferrite (CoFe2O4) nanoparticles (NPs), facilely prepared by a one-pot hydrothermal procedure, were developed for peroxymonosulfate (PMS) activation towards Congo red (CR) degradations. The key experimental parameters were comprehensively investigated to optimize the degradation performance for CR in CoFe2O4/PMS system. Under optimal conditions, the CoFe2O4 NPs exhibited an excellent capability for PMS activation to degrade CR with the degradation efficiency of nearly 100 % in a wide range of pH values (3.0–9.0). The electron paramagnetic resonance (EPR) and quenching experiments confirmed that the entire CR degradation process was dominantly by the non-radical (1O2) and surface-bound SO4·−and ·OH. CoFe2O4 NPs displayed the remarkable stability and reusability, with degradation efficiency of 85.5 % even after six recycles. The possible degradation pathway in CR degradation process was proposed, and the qualitative analysis and ecotoxicity of the degradation intermediates were investigated. This work provided a facile and green strategy to prepare a prospective catalyst for the efficient removal of azo dyes by PMS activation.

Effect of citric acid modification on the properties of hydrochar and pyrochar and their adsorption performance toward methylene blue: crucial roles of minerals and oxygen functional groups.

Modification is widely used to enhance the adsorption performance of pristine hydrochar (HBC) and pyrochar (BC). However, comparisons between modified HBC and BC toward pollutant removal have rarely been reported. In this study, pristine HBC and BC derived from rice straw were first produced, and then citric acid (CA) was used as a modifier to synthesize CA-modified HBC (CAHBC) and CA-modified BC (CABC). Furthermore, the adsorption performance of biochars toward methylene blue (MB) was investigated. The results showed that BC exhibits relatively rough surfaces and contains more minerals (ash), whereas HBC has plentiful O-containing functional groups and fewer minerals. CA modification partially removed minerals from the surface of BC, which weakened the ion exchange, surface complexation, and n-π interaction, resulting in a lower adsorption ability toward MB. By contrast, CA produced more O-containing functional groups on the surface of HBC, which strengthened the hydrogen bonding and electrostatic interaction, thus increasing the adsorption capacity toward MB. The two-compartment model showed a good fit to the adsorption process of MB on CAHBC, and the isotherm data for MB adsorption by HBC and CAHBC are suitable for the Freundlich model. The highest adsorption amount of MB using CAHBC was 80.13mg·g-1, which was 27.66% higher than that for CABC. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy analysis indicated that the carboxyl groups in the surface functional groups of CAHBC played a crucial role in the MB adsorption process. In addition, CAHBC showed a good performance for a wide range of pH values (4.0-10.0) and under the interference of coexisting ions, and also presented a recycling ability. Furthermore, the adsorption of MB on CAHBC biochar was a spontaneous, exothermic, degree-of-randomness-increasing process. Consequently, CA modification of HBC is a promising strategy and could be used for MB removal from aquatic environments.

Purification and activity determination of recombinant human sumo protease’s active region fused with thioredoxin

SUMO (Small Ubiquitin-related Modifier) protease is widely used for recombinant protein expression, but obtaining the protein from derivative sources is challenging due to the degradation during extraction and high costs. In a previous report, we expressed the human SUMO protease’s active region (SENP2) fused with thioredoxin (Trx-SENP2) in E. coli BL21 (DE3). The recombinant fusion protein was soluble. In this study, we present the results of purification and activity evaluation of soluble Trx-SENP2. The enzyme was effectively purified through a single step Ni2 affinity chromatography. Trx-SENP2 was bound to the column in a binding buffer containing 50 mM PBS, 500 mM NaCl, 50 mM imidazol, pH 7.4 and eluted in the basic buffer containing 300 mM imidazol. The purity of the enzyme obtained after purification reached over 98% and yield of Trx-SENP2 was 361 mg/liter of bacterial culture. Importantly, the Trx-SENP2 was biologically active and capable of degrading recombinant SUMO-fused proteins. The protease’s bioactivity, as measured by its ability to cleave SUMO-IL11 into SUMO and IL11 fragments, was 3.33 × 105 U/mg comparable to commercial enzymes. Moreover, the Trx-SENP2 was found to be effective activity under a variety of conditions, including different buffers with high salt and imidazole concentrations and a wide range of pH values. Thus, the properties are useful and easy for the application of the enzyme to cleave recombinant SUMO-fused protein in the process of purification to obtain target proteins. The present study introduces a highly active and easily applicable enzyme for research in recombinant DNA technology.

A super-efficient gel adsorbent with over 1000 times the adsorption capacity of activated carbon

It was observed that a super-efficient gel adsorbent system (RRQG@CDC) could be obtained when a matrix material of polyquaternium gel with a flat distribution (RRQG) was loaded onto a skeleton material of cyclodextrin carbide (CDC). The results showed that the adsorption capacity of RRQG@CDC towards dyes was 1250 times higher than that of commonly used activated carbon, enabling highly efficient purification of dyeing wastewater through superior adsorption. In addition, RRQG@CDC demonstrated adaptability to a range of different pH values and salinity conditions, showing super-efficient adsorption abilities towards various types of dyes. Moreover, simulated scale-up tests confirmed the feasibility of this super-efficient adsorbent for practical engineering applications. An enhanced quasi-planar electrostatic adsorption mechanism model was established, which has changed the traditional understanding of adsorption mechanisms. Furthermore, the waste residues of RRQG@CDC, after dye adsorption, can be directly utilized as high-calorific fuels, showcasing the resourcefulness of these residues while eliminating the risk of secondary pollution. In conclusion, this study achieved a remarkably efficient and resource-based purification of dyeing wastewater by developing a highly effective adsorbent system.

Degradation of phenol by peroxymonosulfate catalyzed by cerium-doped amino-functionalized metal-organic frameworks (NH2-MIL-101 (Fe, Ce))

As an organic pollutant difficult to be degraded in water bodies, phenol is toxic even at low concentrations. Therefore, studying the degradation technology of phenol is of great significance. In order to investigate the effect of transition metal doping on the performance of oxidative degradation of phenol by the persulfate activated by metal-organic frameworks, the different doping levels of Ce were tested based on the NH2-MIL-101(Fe). Then, NH2-MIL-101(Fe,Ce) with different Fe/Ce ratios was successfully prepared by solvothermal method. They were characterized by means of XRD, SEM, TEM, XPS and FT-IR. Selecting phenol as the target pollutant, the NH2-MIL-101(Fe,Ce)/PMS system was constructed to study the degradation rate. The factors of the different temperature, initial pH, anions, Ce doping ratios, catalyst dosage and PMS concentration were investigated. The mechanism of degradation of phenol for the above system was analyzed through free radical burst test, and the metal ion dissolution of catalytic materials in simulated wastewater treatment process was monitored by ICP-OES instrument. Finally, the intermediate products of phenol in the degradation process were inferred using LC-MS method. The results showed that when the molar ratio of Ce/(Ce+Fe) was 15 %, under the same reaction conditions, NH2-MIL-101(Fe,Ce)-15 % (referred to as NM-15 %) had the highest degradation rate for phenol. After the 50 min, phenol could be almostly completely removed, with K value of 0.059 min−1. This system could achieve the efficient degradation of phenol under the range of pH values (pH=3–9). The results of the free radical burst test and the free radical trapping test showed that the dominant oxidising groups were SO4•−, •OH, •O2− and non-free radical 1O2.

Physical properties of soft contact lens multipurpose solutions commercially available in Ghana

PurposeTo investigate the physical properties of commercially available multipurpose soft contact lens solutions in Ghana. MethodspH (Kelilong ICL-099 pH meter, China), osmolality (OSMOMAT 3000, GONOTEC, Germany), surface tension (Sigma 700 Tensiometer, Sweden), and viscosity (CFOC-200 Viscometer, Cannon Company, USA) of various soft contact lens multipurpose solutions (MPS) were measured in triplicates at room temperature. Viscosity measurements were also taken at 34 °C ocular surface temperature. The solutions examined were Opti-Free Replenish (OFR), Trufresh (TF), Avizor (AV), Freshlook (FL), and Refresh (RF). ResultsSeveral solutions were largely hypo-osmotic in the range of 108–231 mOsm/kg, the exception being Avizor, which had osmolality values that were closer to human tears (301 ± 0.58 mOsm/kg). The range of pH values of the solutions (6.33–8.24, mean (SD) = 7.53 ± 0.18) fell within the reported tolerable range for the ocular surface (6.20–9.00). Surface tension values ranged from 35.86 to 42.27 mNm with a mean of 38.49 ± 2.32 mNm. The average viscosity of most solutions at room temperature (25 °C) was 1.44 ± 0.49 cP with a range of 1.04–2.15 cP. Significantly lower values ranging from 0.79 to 1.58 cP were obtained at ocular surface temperature (34 °C), p = 0.0001). ConclusionsThe physical properties of many of the solutions used as MPS in Ghana are markedly variable. Nevertheless, pH, surface tension, and viscosity fall within the acceptable limits of ocular physiological tolerance; except for osmolality, which majority were outside the reported tolerable range for the ocular surface. This information may partly explain the reason some patients exhibit strong preferences for certain care systems and should aid clinical decision-making when prescribing eye care systems to patients.