Varying pH Values Research Articles

A rapid colorimetric sensor for the detection of mercury in environmental samples employing 2 aminobenzohydrazide schiff base functionalized silver nanoparticles

Mercury (Hg2+) is an extremely toxic and dangerous element for living organisms. Herein, a simple and selective sensor based on the Schiff base of 2-aminobenzohydrazide with triazole thiazole substituted vanillin (EAHT) functionalized silver nanoparticles (EAHT-AgNPs) is proposed for the detection of Hg2+ in environmental water samples. The chemical reduction method was employed to synthesize EAHT-AgNPs using sodium borohydride as the reducing agent. The synthesized nanoparticles were initially confirmed by UV-visible and FTIR spectroscopy, followed by analysis with a zeta sizer to determine their average size, surface charge and polydispersity index. The atomic force microscopy (AFM) and scanning electron microscopy (SEM) were employed to determine the size and morphology of EAHT-AgNPs. Additionally, the functionalized particles exhibited stability at varying pH values, salinity concentrations and elevated temperature. The addition of Hg2+ altered the yellow color of EAHT-AgNPs to colorless, confirming the complex formation. The analytical response constructed as a decrease in absorbance versus concentration showed linearity (R2 = 0. 991) from 0.1 to 100 µM with a limit of detection of 0.04 µM (40 nM) and limit of quantification of 0.085 µM (85 nM). The sensor was successfully applied for the detection of Hg2+ ions in tap water. In conclusion, Schiff base of 2-aminobenzohydrozide with triazole thiazole substituted vanillin silver nanoparticle-based chemosensor is highly sensitive and selective for the detection of Hg2+ in water samples. The proposed sensor has been applied for mercury detection tap water, future research should explore its applications in more complex samples like industrial wastewater and marine environments. Further, studies may focus on the integrating of the approach into the portable devices such as smartphone for on-site detection of mercury.

Advanced solar-driven hydrogel sponge for efficient heavy metal wastewater purification and clean water production through interfacial evaporation

Solar-driven interfacial evaporation (SDIE) technology represents a promising solution for freshwater harvesting, characterized by its cost-effectiveness, eco-friendliness, and sustainability. Nevertheless, achieving efficient removal of heavy metal ions during the SDIE process remains a significant challenge. In this study, we present a cost-effective method to construct a hybrid hydrogel evaporator by incorporating the konjac glucomannan (KGM) and reduced graphene oxide (rGO) into a polyvinyl alcohol (PVA) network. The hybrid hydrogel evaporator features a three dimensional layered structure, full spectrum absorption capability, high stability and inherent salt diffusion ability. These characteristics enabling a evaporation rate of 1.61 kg m−2 h−1 from wastewater across varying pH values (2-12) and high salinity levels (1 kW m-2). Significantly, the hybrid polymer network within the hydrogel is rich in -OH groups, enabling concurrent wipe off heavy metal ions and organic dyes from wastewater. The results in a ten thousand times reduction in the concentration of heavy metals such as Cr3+, Mn2+, Cu2+, Zn2+, and Pb2+ in the wastewater. This study provides new insights into solar evaporation technology and contributes to addressing challenges related to water scarcity.

Exploring the potential of CdSe nanostructured thin films for energy conversion and environmental remediation

Abstract The rapid thermal evaporation method was employed to prepare cadmium selenide (CdSe) nanostructured thin films with varying thicknesses on glass and FTO substrates. The films were characterized for their structural, optical, and electrochemical properties. Scanning electron microscope (SEM) analysis revealed inhomogeneous surfaces with particle sizes ranging from 18 to 46 nm. The photocatalytic performance of the CdSe films was evaluated by the degradation of methylene blue (MB) dye under visible light, with varying pH values, achieving a degradation efficiency of 100 % at pH 10 after 180 minutes. Photocurrent density measurements demonstrated the films' ability to sense visible light. We performed a cyclic voltammetry (CV) measurement and analyzed the CV curves of the CdSe nanostructured thin film electrodes. It clearly shows that the CV curves had a rectangular shape, which suggests that EDLC behavior was present and non-faradaic capacitance was the main type. The photoconversion efficiency measured is 1.4858 at a bias voltage of 0.66 V under illuminated conditions. Nonlinear optical properties were conducted for CdSe nanostructured thin films.

Evaluation of sensitivity in a vertically misaligned double-gate electrolyte-insulator-semiconductor extended source tunnel FET as pH sensor

In this research, the primary objective is to investigate the impact of vertical gate misalignment on the source and drain regions of 30 nm. The double-gate Electrolyte-Insulated-Semiconductor extended-source Tunnel Field-Effect Transistor (ES-VTFET) is proposed for its potential application as a pH sensor. The gate electrode cannot be perfectly aligned with the channel due to fabrication tolerances, particularly in very short-channel structures. This study aims to introduce a vertical electrolyte Bio-TFET-based pH sensor capable of detecting pH changes in aqueous (electrolyte) solutions. The effect of variation in pH values on the electrical characteristics of the device such as drain current (IDS), transconductance (gm), voltage sensitivity (SV) and current sensitivity (SI) have been examined. It has been assumed that the electrolyte section is an intrinsic semiconductor material where electrons and holes signify mobile ions in aqueous solutions. The electrolyte region has an electrolyte dielectric constant of 78, an energy bandgap of 1.12 eV, and an electron affinity of 1.32 eV. Finally, the gate misalignment aspect of the proposed bio TFET-based pH sensor is emphasized by comparing sensitivity parameters. Hence, the proposed pH sensor can be used as a potential candidate for the futuristic application of biosensors.

In Vitro Susceptibility and Synergistic Effect of Bismuth Against Helicobacter pylori

Background/objectives: Bismuth is commonly used in Helicobacter pylori (H. pylori) eradication therapy. However, few studies have examined the in vitro susceptibility of H. pylori to bismuth. Moreover, the exact mechanism of action of bismuth on H. pylori remains unclear. The aim of this study was to identify the anti-bacterial effect of bismuth as well as to evaluate potential synergistic effects between bismuth and various antibiotics. Methods: The minimum inhibitory concentrations (MICs) of three bismuth preparations, bismuth subsalicylate, bismuth potassium citrate, and colloidal bismuth subcitrate (CBS, De-Nol) were determined for H. pylori strains using the agar dilution technique. Agar plates of varying pH values from 5.0 to 8.0 were used to investigate whether acidity influences the anti-bacterial effect of bismuth. A checkerboard assay was performed to assess the synergism between CBS and antibiotics (amoxicillin, clarithromycin, and metronidazole). Results: Twelve H. pylori strains, including three reference strains (H. pylori 26695, J99, and ATCC 43504), and nine clinically isolated strains were tested. The MICs for bismuth subsalicylate, bismuth potassium citrate, and CBS ranged from 4 to 32 μg/mL, 2 to 16 μg/mL, and 1 to 8 μg/mL, respectively. The bismuth MICs for the reference strains were similar at pH 5–8. In the checkerboard assay, no interactions between CBS and any of the antibiotics were observed in the reference H. pylori strains. Conclusions: Bismuth showed in vitro susceptibility against H. pylori. The enhanced eradication efficacy of bismuth-containing regimens appears to be due to mechanisms other than direct synergy with antibiotics.

Egg Yolk, a Multifunctional Emulsifier: New Insights on Factors Influencing and Mechanistic Pathways in Egg Yolk Emulsification

Egg yolk is a highly effective natural emulsifier used in various food products. Its emulsifying properties are influenced by food product chemical conditions, and processing methods. Nevertheless, to effectively utilize egg yolk in food products, a more comprehensive understanding of these factors is crucial. This review discusses recent developments regarding how factors like pH, ionic strength, thermal treatments, enzymatic treatments, and novel non-thermal treatments affect egg yolk emulsifying properties. It also explores the underlying mechanisms involved in egg yolk emulsification. Food products involve different ingredients leading to varying pH values and ionic strength, which affect egg yolk protein adsorption and emulsion stability. Processing steps like thermal treatment can damage egg yolk proteins, reducing their emulsifying capabilities and leading to unstable products. Incorporating sugar, salt, and amino acids can enhance egg yolk’s resistance to heat and preserve its ability to form stable emulsions. As an alternative to thermal treatment, non-thermal techniques such as high-pressure processing and high-intensity ultrasound can be employed to preserve egg yolk. Furthermore, forming egg yolk–polysaccharide complexes can enhance egg yolk emulsifying properties. These advancements have facilitated the creation of egg yolk-based products such as high internal phase Pickering emulsions (HIPEs), low-fat mayonnaise, and egg yolk gels. A comprehensive understanding of the emulsifying mechanisms and factors involved in egg yolk will be instrumental in improving food quality and creating novel egg yolk-based products.

Modelling of SARS-CoV-2 spike protein structures at varying pH values

ABSTRACT Recognising the fact that the SARS-CoV-2 spike glycoprotein is the most crucial protein for the virus's attachment to surfaces and subsequent infection, we carried out massive all-atom molecular dynamics studies of the conformational states of S-protein in solvents of various pH values, ranging from pH = 1 through pH = 11. Our studies found that: (1) The S-protein’s structural deviation measured in the backbone at pH = 1 is 185% higher than that of pH = 7, and most of this overall deviation occurs at the receptor-binding domain and N-terminal domain. (2) Structural changes are also observed at both pH = 3 and pH = 11, albeit to a lesser extent than at pH = 1. (3) Changes, as measured by various metrics at pH = 5, pH = 7 and pH = 9, are insignificant. Such a high degree of structural tolerance of the S-protein at these pH values corroborates indirectly with in vitro observations that the virus retains significant infectivity over a wide range of pH. The multiscale structural analyses pinpoint the critical regions that are responsible for the S-protein’s structural deviations.

Impact of Plastic Mulching on Soil Properties and Heavy Metal Dynamics in Agricultural Systems: A Case Study from Manikganj, Bangladesh

This research study examines the impact of different types and sizes of plastics on various soil properties. Clay loam soil samples were collected from Paril village, Manikganj district, Bangladesh, and subjected to plastic incubation experiments. The plastics underwent 180 days of intense ultraviolet (UV) radiation to simulate natural sunlight degradation. The soil samples were mixed with three types of plastics (P1, P2, P3) and two sizes (1mm, 10mm) in individual pots, with and without the addition of zinc sulfate. The soil properties, including pH, total dissolved solids (TDS), available zinc, cation exchange capacity (CEC), nitrogen content, and total phosphorus, were analyzed using various techniques. The results indicate significant variations in pH and TDS values influenced by plastic size and type. The available zinc content differed among plastic types, and plastic size affected CEC values. Nitrogen content was influenced by plastic size, with smaller particles having a greater impact. Total phosphorus content varied with different plastic types. These findings contribute to our understanding of the potential effects of plastics on soil properties and highlight the need for further investigation into the underlying mechanisms.

Development of a mobile application for rapid detection of meat freshness using deep learning

The freshness or spoilage of meat is critical in terms of meat color and quality criteria. Detecting the condition of the meat is important not only for consumers but also for the processing of the meat itself. Meat quality is influenced by various pre-slaughter factors including housing conditions, diet, age, genetic background, environmental temperature, and stress factors. Additionally, spoilage can occur due to the slaughtering process, though post-slaughter spoilage is more frequent and has a stronger correlation with postslaughter factors. The primary indicator of meat quality is the pH value, which can be high or low. Variations in pH values can lead to adverse effects in the final product such as color defects, microbial issues, short shelf life, reduced quality, and consumer complaints. Many of these characteristics are visible components of quality. This study aimed to develop a mobile application using deep learning-based image processing techniques for the rapid detection of freshness. The attributes of the source and the targeted predictions were found satisfactory, indicating that further advancements could be made in developing future versions of the application.

Storehouse of Peculiar Supramolecular Architecture: Probing the Charge-Transfer Phenomenon and Effect of Altering the pH in a Meta-Oriented Single Donor-Double Acceptor Fluorophore.

The investigation of excited-state intramolecular charge transfer (ESICT) has been a fascinating area of research. Although the ESICT events have been studied mostly for para-disubstituted donor-acceptor type molecules, the meta-oriented donor-acceptor type molecules have also shown tremendous potential as ESICT active molecules. In the current work, a small fluorescent probe diethyl 5-amino isophthalate (DE-5A-IPA) was investigated as a potential model to investigate ESICT events in the solution as well as solid phase. DE-5A-IPA was synthesized easily starting from commercially available 5-amino isophthalic acid in excellent yield. In the solid state, differing extents of CH···π-type binding led to formation of fully planar and puckered "cyclobutane" mimic supramolecular architecture, as evidenced from the crystal structure analysis. In addition, the single crystal structure of DE-5A-IPA shows that the donor (-NH2) and acceptor (-CO2Et) are situated in the same plane, thereby assuring the prerequisites of a through-space charge transfer. DE-5A-IPA undergoes noticeable Stokes shift (in cm-1) when the polarity of the medium was changed (4820 cm-1 in hexane; 9375 cm-1 in water). The excited-state dipole moment (μe) was calculated to be 4.0 units higher than the ground-state dipole moment (μg). DE-5A-IPA had an appreciable quantum yield (0.10 ± 0.03 to 0.27 ± 0.04). The ESICT phenomenon was also investigated by ground- and excited-state structural calculations using Gaussian 16 software. The excited-state lifetime measured by the time correlated single photon counting technique was found to vary with the polarity of the solvent, thereby providing further support to the ESICT phenomenon being operative in DE-5A-IPA. Taking advantage of the -NH2 group (which is susceptible to protonation) in DE-5A-IPA, steady state and time-resolved photodynamics were investigated in solutions of varying pH values. Interestingly, the emission quantum yields as well as the emission lifetime increase with an increase in pH value, thereby establishing DE-5A-IPA as a pH-sensitive probe. The current findings shall boost the understanding of meta-oriented ESICT enabled compounds in terms of their excited-state photophysics.

Characterization of Robusta Coffee Powder with Addition of Palm Sugar and Vanilla Powder to Improve The Quality of Robusta Coffee (Coffea canephora Pierre)

Bondowoso Robusta Coffee is a type of Robusta coffee that has a distinctive taste and high quality. The distinctive taste and high quality are obtained from the results of harvest management and post-harvest processing in accordance with Standard Operating Procedures (SOP). This research will be carried out by testing the characteristics of Robusta ground coffee with a mixture of palm sugar and vanilla flavoring to improve the quality of Robusta ground coffee. This was done by knowing the physicochemical and organoleptic properties of the mixed Robusta ground coffee. The aim of this research is to determine the interaction between roasting level and the composition of palm sugar and vanilla powder on the physiochemical and organoleptic properties of 3 in 1 Robusta Coffee. This research uses an experimental plan arranged factorially with the basic pattern of a Completely Randomized Design (CRD) with 4 replications. This design has two factors, the first factor is the roasting level and the second is the mixture composition. The results of this research show (1) The interaction of Roasting Level and Mixture (palm sugar and vanilla powder) has no significant effect on all observed variables such as water content, Brix content, pH value, and powder bulk density. (2) The effect of the main level of roasting has a very significant effect on the observed variables of rainfall density and an insignificant effect on the variables of air content, Brix content and pH value. (3) The effect of the main mixture has a very significant effect on the observed variables of air content, Brix content and powder bulk density and has no significant effect on the variable pH value.

Separating Hofmeister Trends in Stern and Diffuse Layers at a Charged Interface.

Understanding the role of pH and ions on the electrical double layer (EDL) at charged mineral oxide/aqueous interfaces remains crucial in modeling environmental and industrial processes. Yet the simultaneous contribution of pH and specific ion effects (SIEs) on the different layers of the EDL remains unknown. Here, we utilize zeta potential measurements, vibrational sum frequency generation, and the maximum entropy method to ascertain the detailed structure of the Stern and diffuse regions of the EDL at the silica/water interface with varying pH values for different alkali chlorides. Both at pH 2, when the surface is nearly neutral, and at pH 12, when the surface is highly charged, we observe that Li+ and Na+ disrupt while Cs+ enhances existing water structures within the Stern layer. Moreover, the SIE trends for the diffuse and Stern layers are opposite to one another at pH 2 (in the amount of ordered water) and at pH 12 (in the amount of net oriented water). Finally, we observe an inversion in Hofmeister (SIE) trends at low and high pH in the zeta that impacts the diffuse layer structure. These results indicate that SIEs play critical yet separable roles in governing both the electrostatic and water-structuring capabilities of the EDL.

Exploring gelation properties and structural features on 3D printability of compound proteins emulsion gels: Emphasizing pH-regulated non-covalent interactions with xanthan gum

Rational regulation of pH and xanthan gum (XG) concentration has the potential to modulate interactions among macromolecules and enhance 3D printability. This study investigated non-covalent interactions between XG and other components within compound proteins emulsion gel systems across varying pH values (4.0–8.0) and XG concentrations (0–1 wt%) and systematically explored impacts of gelation properties and structural features on 3D printability. The results of rheological and structural features indicated that pH-regulated non-covalent interactions were crucial for maintaining structural stability of emulsion gels with the addition of XG. The 3D printability of emulsion gels would be significantly improved through moderate depletion flocculation produced when XG concentration was 0.75 wt% at the pH 6.0. Mechanical properties like viscosity exhibited a strongly negative correlation with 3D printability, whereas structural stability showed a significantly positive correlation. Overall, this study provided theoretical insights for the development of emulsion gels for 3D printing by regulating non-covalent interactions.

Effects of anions on the electrospray ionization of proteins in strong acids.

The effect of anions on the positive electrospray ionization (ESI) of proteins in different strong acids with varying pH values from 3 to 1 is studied using high-pressure ESI. Reducing the pH from ∼2 to 1 caused a drastic shift in charge state from a high-charge-state distribution (HCSD) to a narrow low-charge-state distribution (LCSD). The shift in charge state was consistent with the circular dichroism result that showed a conformational change due to the "acid-induced folding" of proteins from an unfolding state to a compact molten globule state. Acids of different anions produced noticeable differences in the average charge for HCSD and LCSD. For HCSD, the average charge was lower than the value typically observed using formic and acetic acids. As for LCSD, the average charge was lower than the "native" charge. The high abundance of acid anion that induces the protein compaction was believed to play a role in charge reduction. The effectiveness of anions to "refold" a highly unfolded protein to a compact state and the propensity to reduce the charge of HCSD for proteins appeared to follow the selectivity series of anions towards the stationary phase in ion chromatography. However, the propensity of anions to reduce the charge for LCSD follows quite an opposite trend. The presence of ammonium salt in the acidic solution was found to increase the charge of LCSD. The simple mass spectrum with a narrow distribution of charge state obtained with perchloric acid at pH 1 was demonstrated to facilitate the counting of basic sites.

Electrochemical Detection of Ornidazole By Means of an Electrode Modified with Copper-Iron Nanoparticles and Carbon Black

Antibiotics have become fundamental tools in our fight against disease but their accumulation in the aquatic environment due to discharges from manufacturing plants, hospitals and farms, and to misuse by the public has seen them emerge as water pollutants. Their presence constitutes a serious environmental and health risk due to their toxicity and due to the risk of antimicrobial resistance (AMR), which may render antibiotics ineffective when employed to fight infection. Assessing the impact of antibiotic pollution on water quality, drinking water, recreational/bathing water, and the impact on life is critical for our health and wellbeing.Ornidazole is a member of the nitroimidazole antibiotic family that is heavily employed in the treatment of both human and animal infections [1]. This widespread use has led to the accumulation of the antibiotic in aquatic environments, posing a serious health risk due to its toxicity and the risk of AMR [2]. For this reason, novel and environmentally friendly methods of rapidly and accurately detecting its presence in the environment are vital to mitigate its pollution and harmful effects.In this study two materials are combined to enhance the conductivity and ability of a glassy carbon electrode sensor to detect ornidazole. Carbon black, a material composed of 95% carbon with a structure similar to graphite [3] is functionalized using a novel green method with tannic acid. This is then combined with a layered double hydroxide (LDH) to act as a source of metal nanoparticles. LDH’s are a combination of transition metals with the general formula [M1-x 2+M3+ x(OH)2]x+(An-)x/n.mH2O where M is two different metals and A is the intercalated anion between the stacked layers of M2+/M3+ ions to produce a 2D layered nanosheet structure [4]. These LDHs are synthesized hydrothermally, which involves combining sources of the desired metals into a sealed autoclave and heating to produce a high vapour pressure environment.Functionalized carbon black was dispersed and drop-casted onto the surface of the electrode. After drying, it was decorated by means of drop-casting with a dispersion of the LDH containing the desired elements. The LDH is then easily reduced by means of cyclic voltammetry to embed the nanoparticles of the desired elements into the carbon black, producing a stable modified electrode. LDH’s containing a variety of elements were investigated for their ability to detect ornidazole. The optimum element combination was concluded to be copper-iron nanoparticles. The procedure for the synthesis and modification of the electrode can be seen in Figure 1.The carbon black-copper iron (CuFe) modified sensor shows excellent sensitivity compared to bare glassy carbon and is capable of detecting ornidazole concentrations from 0.2 μM to 600 μM, displaying excellent stability over multiple uses. Studies were performed to characterize the carbon black-CuFe material using SEM, XRD, XPS, FTIR, and EDX. Investigations were carried out into the behaviour of the sensor at varying pH values and to determine the reaction kinetics of detection. To study the selectivity of the sensor interferants were introduced to the antibiotic solution and experiments were performed in real water samples gathered from various locations.[1] Q. Wang, C. Wang, Q. Wang, & Z. Wang, Journal of Agricultural and Food Chemistry., 2019, 67(41), 11527-11535[2] W. El, N. Tajat, A. Idelahcen, M. Tamimi, S. Qourzal, A. Assabbane, & I. Bakas, Microchemical Journal, 2023, 195, 109397[3] J. M. Martín-Martínez, Adhesion Science and Engineering : Surfaces, Chemistry and Applications, 2002, Chapter 13, 573-675[4] A., Karmakar, K., Kannimuthu, S., Sam Sankar, K., Sangeetha, R., Madhu, & S., Kundu. Journal of Materials Chemistry A. 2020 Figure 1

Layered Double Hydroxides As a Method for Decorating Electrodes with Metal Particles for Sensing the Antibiotic Ornidazole

The use of metallic particles and nanoparticles to improve the detection capabilities of sensors has been widely reported in literature and thus, a method of decorating electrodes reliably and easily with metallic particles is of great interest. In this regard, Layered Double Hydroxides (LDHs) are of particular interest to act as a source of metal particles. LDHs are inorganic two-dimensional compounds with the general formula [M1-x 2+M3+ x(OH)2]x+(An-)x/n.mH2O where M is two different metals and A is the intercalated anion between the stacked layers of divalent and trivalent M2+/M3+ ions to produce a 2 nanosheet structure [1]. In this study LDHs are synthesised hydrothermally, which involves placing metallic salts of the desired metals into an aqueous solution in a sealed autoclave and heating to a high temperature to produce a high vapour pressure environment. From this method various elements can be combined to produce bimetallic and trimetallic LDHs.The obtained LDH powder is then dispersed in ethanol and water using ultrasonication and layered onto the electrode surface by means of drop-casting. It can then be easily reduced using cyclic voltammetry to act as an efficient method of decorating an electrode with metallic particles of the desired elements. In this study, a variety of layered double hydroxides were synthesised using combinations of different elements and then subsequently used to reduce metal particles onto a glassy carbon electrode.A variety of bimetallic and trimetallic LDH compounds containing copper, iron, cobalt, and nickel were investigated. To compare the sensing capabilities of these reduced metal particles, the reduction of the antibiotic ornidazole was used as an analyte. Ornidazole is a member of the nitroimidazole antibiotic family that is heavily employed in the treatment of both human and animal infections [2]. This widespread use has led to the accumulation of the antibiotic in aquatic environments, posing a serious health risk due to its toxicity and the risk of antimicrobial resistance [3]. Thus, a sensor capable of quickly and reliably detecting the antibiotic is of great importance. To enhance the conductivity of the modified sensors, a drop-casted layer of functionalised carbon black was combined with the metallic particles.For the detection of ornidazole, the copper-iron (CuFe) particles were concluded to be optimum, displaying a detection range of 0.2 uM to 600 uM. Characterisation studies were performed on the CuFe particles using SEM, XRD, XPS, FTIR, and EDX. Investigations were carried out into the behaviour of the sensor at varying pH values and to determine the reaction kinetics of detection. To study the selectivity of the sensor interferants were introduced to the antibiotic solution and experiments were performed in real water samples gathered from various locations.[1] A., Karmakar, K., Kannimuthu, S., Sam Sankar, K., Sangeetha, R., Madhu, & S., Kundu. Journal of Materials Chemistry A. 2020[2] Q. Wang, C. Wang, Q. Wang, & Z. Wang, Journal of Agricultural and Food Chemistry., 2019, 67(41), 11527-11535[3] W. El, N. Tajat, A. Idelahcen, M. Tamimi, S. Qourzal, A. Assabbane, & I. Bakas, Microchemical Journal, 2023, 195, 109397

Role of Ammonia in Aerosol Liquid Water, pH, and Secondary Inorganic Aerosols Formation at an Ammonia-rich City in Changzhou

Ammonia （NH3） is an important alkaline reactive nitrogen, which, as a precursor of fine particulate matter, raises public health issues. In this study, online NH3, SO2, NO2, PM2.5, and its water-soluble inorganic ions were detected to deduce the influence of NH3 on aerosol liquid water content （AWC） and aerosol pH, including the formation of water-soluble secondary ions in PM2.5 in winter in Changzhou, an ammonia-rich city in the Yangtze River Delta area in winter. The results showed that NH4+ mainly existed in the form of NH4NO3 and （NH4）2SO4, and the remaining NH4+ existed as NH4Cl. Owing to the NH3-NH4+ buffer system, the aerosol pH values were found at 4.2 ± 0.4, which was positively correlated with the NH3 content. The aerosol pH value variation narrowed with the increase in PM2.5 concentration and tended to be between 4 to 5. AWC increased exponentially with the increase in humidity and SNA content, among which NH4NO3, （NH4）2SO4, and NH4Cl contributed 58.5%, 18.4%, and 8.3%, respectively, due to their hygroscopicity. Aerosol pH, AWC, and NH3-NH4+ conversion promoted the gas-to-particle conversion of SO2 and NO2. In Changzhou, rich NH3-NH4+ were found to maintain relatively high pH values, push up AWC, and promote the heterogeneous reaction of SO2, whereas NO3- generation was dominated by a homogeneous reaction, which was accelerated by NH3. According to the simulation results, relatively noticeable changes in aerosol pH and AWC could be found by the reduction of up to 30% of NH3.

Synthesis and properties of pH‐dependent Gemini surfactant containing tripeptide structure

AbstractAmino acid surfactants have mild performance and are sourced from renewable biomass. Compared to classical surfactants, Gemini surfactants have superior properties. The amino acid Gemini surfactants are believed to be adopted more widely. The Gemini surfactant with tripeptide structure, sodium di(lauroyl glutamyl) lysine (DLGL), was prepared by amidation utilizing methyl laurate, glutamate and lysine and characterized by 1H NMR, 13C NMR and MS. Additionally, the pKa value, surface activities, aggregation, foaming properties and emulsifying attributes of the DLGL surfactant in aqueous solution with varied pH values were examined. The results indicate that the protonation‐deprotonation behavior of the DLGL surfactant is highly dependent on pH values. The surface tension, critical micelle concentration (cmc), foamability and foam stability exhibited superior performance at pH 6 and 7. Conversely, superior emulsifying ability was observed at pH 9 and 10. Moreover, the spherical vesicles were formed by the DLGL surfactant at pH 6, 7 or 8 while the micelles were generated at pH 9 or 10.

Application of a Novel Dissolution Medium with Lipids for In Vitro Simulation of the Postprandial Gastric Content.

Food can change various physiological parameters along the gastrointestinal tract, potentially impacting postprandial drug absorption. It is thus important to consider different in vivo conditions during in vitro studies. Therefore, a novel dissolution medium simulating variable postprandial pH values and lipid concentrations was developed and used in this study. Additionally, by establishing and validating a suitable analytical method, the effects of these parameters on the dissolution of a model drug, cinnarizine, and on its distribution between the lipid and aqueous phases of the medium were studied. Both parameters, pH value and lipid concentration, were shown to influence cinnarizine behavior in the in vitro dissolution studies. The amount of dissolved drug decreased with increasing pH due to cinnarizine's decreasing solubility. At pH values 5 and 7, the higher concentration of lipids in the medium increased drug dissolution, and most of the dissolved drug was distributed in the lipid phase. In all media with a lower pH of 3, dissolution was fast and complete, with a significant amount of drug distributed in the lipid phase. These results are in accordance with the in vivo observed positive food effect on cinnarizine bioavailability described in the literature. The developed medium, with its ability to easily adjust the pH level and lipid concentration, thus offers a promising tool for assessing the effect of co-ingested food on the dissolution kinetics of poorly soluble drugs.

Assessment on the Impact of Mining and Industrial Activities in Groundwater Quality in Chandrapur, Maharashtra Through Remote Sensing and GIS Applications

This study evaluated the quality of groundwater in Chandrapur Taluka, Maharashtra, using geospatial techniques and data from 2014 and 2018. The study assessed various water quality parameters such as chloride, fluoride, pH, residual sodium carbonate (RSC), and sodium adsorption ratio (SAR). The findings showed that chloride concentrations were mostly within acceptable limits, but there was a slight increase in areas near mining and industrial sites, which was statistically significant (p < 0.05). Fluoride levels were generally within permissible bounds, but there was a noticeable increase near industrial areas in 2018 compared to 2014, which was statistically significant (p < 0.05) and raised environmental concerns. Variations in pH values were also observed, which could impact aquatic ecosystems, with a decrease noted from 2014 to 2018. RSC levels were higher near mining and industrial zones in 2018, exceeding recommended limits, indicating a potential threat to water quality. SAR levels in 2018 were higher, potentially impacting agriculture, but still within acceptable limits. Sulphate levels showed a reduction from 2014 to 2018. These comprehensive findings highlight the specific impacts of mining and industrial activities on groundwater quality and raise broader scientific questions. They can be used to develop evidence-based policies for effective mitigation measures and engage a wider readership.