Weak Base Research Articles

Synthesis of S-Allyl-O, O′-Dibutyl Phosphorodithioate and Its Adsorption Mechanism on Chalcopyrite Surface

The demand for non-ferrous copper metals has increased dramatically with the development of the global economy; accordingly, some refractory copper sulfide ores with low grade and their associated minerals are beginning to be utilized, making the flotation separation of copper concentrates exceptionally difficult, especially the separation of chalcopyrite and pyrite. In this paper, S-allyl-O, O′-dibutyl phosphorodithioate (ADTP) was synthesized by a one-pot method and used as a chalcopyrite collector in the flotation separation of chalcopyrite and pyrite. Flotation experiments results have shown that ADTP exhibits better selectivity and greater collecting power for chalcopyrite under neutral or weak base conditions. The 95% recovery of chalcopyrite can be achieved at pH 8.0 and 8.0 mg/L ADTP. From the analysis results of the contact angle, the SEM-EDS spectrogram, and elemental mapping, it was found that ADTP adsorbed uniformly on a chalcopyrite surface and made a significant contribution to the hydrophobicity of the surface. Confirmed by FTIR and XPS analysis, ADTP was able to form P–S–Cu bonds on a chalcopyrite surface, proving that it was adsorbed on the chalcopyrite surface in the form of chemisorption.

On the Need to Develop a Federal Program to Optimize the Economic Base of Public Control in Russia

Annotation. This article is devoted to the analysis of the prospects for the development and adoption of a federal program aimed at optimizing the economic basis of public control in the Russian Federation. The authors substantiate the position that one of the main problems hindering the development of public control in the country is its weak economic base. Due to the fact that public authorities play an important role in the process of formation and functioning of subjects of public control in Russia, the basis for financing the organization and activities of public control are funds from state and municipal budgets. In this regard, the authors substantiate the need for the development and adoption by the Government of the Russian Federation of a comprehensive federal program dedicated to strengthening organizational, technological, material and property independence and independence of subjects of public control. The work substantiates the need to include in the draft of the above-mentioned federal program sections devoted to: ensuring the material and technical independence of subjects of public control from public authorities; ensuring their financing primarily from protected items of public budgets; development of processes for the use of modern information and communication technologies by these entities; consolidation of a system of criteria for assessing the effectiveness and efficiency of the work of subjects of public control as the main condition for increasing the volume of their funding; consolidating a system of control on the part of public authorities regarding budget financing of the activities of these entities; systems for organizing public-private partnerships in the field of public control. In addition, the work substantiates the system of proposals for participation in the development of the above-mentioned federal program of the country's Public Chamber.

RESULTS OF EXPERIMENTAL TRAY STUDIES OF THE SOIL FOUNDATION BASE REINFORCED WITH MICROPILES

Purpose. Obtaining a change in the deformed state of models of unreinforced and reinforced micropile soil base to determine the influence of the reinforcement element. Methodology. The method of research in a flat tray was used, which makes it possible to solve a certain range of tasks related to the interaction of foundations with the soil base. The conditions for conducting experimental research and the features of creating models of unreinforced and micropile reinforced soil bases are given. The conditions for creating clay paste, laying it in a flat tray, preparing the model for loading, and taking measurements are given in detail. To assess the adequacy of experimental tray studies, modeling conditions were calculated based on the parameters of a real civil structure, its foundation and soil base. Findings. During the experimental studies of the soil foundation and its interaction with the base in a flat tray, two series of experiments were conducted, three experiments in each series. In series Nos. 1-3, an unreinforced base was studied, in series Nos. 4-6, a base reinforced with a single micropile. Vertical displacements were averaged, which were measured by three dial indicators installed in the middle and on both sides of the die that modeled the foundation. On the basis of the results obtained during the experimental studies, diagrams were plotted in σ – s coordinates (stress – settlement). Originality. The originality of the work consists of obtaining a change in the deformed state of the models of unreinforced and micropile reinforced soil base and determining the influence of the reinforcement element (the maximum vertical displacement of 14.7 mm in the model reinforced with micropile in contrast to 17.5 mm in the unreinforced one, i.e., the reduction of this component of the deformed state by 1.19 times). Practical value. The practical value of the conducted research lies in the proof of the positive impact of micropiles based on the results of experimental tray studies. Based on the obtained results, it is reasonable to apply micropiles created with the help of drilling-mixing technology to successfully reduce the vertical displacements of the foundations of civil structures on weak soil bases.

Drug Crystal Precipitation in Biorelevant Bicarbonate Buffer: A Well-Controlled Comparative Study with Phosphate Buffer.

The purpose of the present study was to clarify whether the precipitation profile of a drug in bicarbonate buffer (BCB) may differ from that in phosphate buffer (PPB) by a well-controlled comparative study. The precipitation profiles of structurally diverse poorly soluble drugs in BCB and PPB were evaluated by a pH-shift precipitation test or a solvent-shift precipitation test (seven weak acid drugs (pKa: 4.2 to 7.5), six weak base drugs (pKa: 4.8 to 8.4), one unionizable drug, and one zwitterionic drug). To focus on crystal precipitation processes, each ionizable drug was first completely dissolved in an HCl (pH 3.0) or NaOH (pH 11.0) aqueous solution (450 mL, 50 rpm, 37 °C). A 10-fold concentrated buffer solution (50 mL) was then added to shift the pH value to 6.5 to initiate precipitation (final volume: 500 mL, buffer capacity (β): 4.4 mM/ΔpH (BCB: 10 mM or PPB: 8 mM), ionic strength (I): 0.14 M (adjusted by NaCl)). The pH, β, and I values were set to be relevant to the physiology of the small intestine. For an unionizable drug, a solvent-shift method was used (1/100 dilution). To maintain the pH value of BCB, a floating lid was used to avoid the loss of CO2. The floating lid was applied also to PPB to precisely align the experimental conditions between BCB and PPB. The solid form of the precipitants was identified by powder X-ray diffraction and differential scanning microscopy. The precipitation of weak acids (pKa ≤ 5.1) and weak bases (pKa ≥ 7.3) was found to be slower in BCB than in PPB. In contrast, the precipitation profiles in BCB and PPB were similar for less ionizable or nonionizable drugs at pH 6.5. The final pH values of the bulk phase were pH 6.5 ± 0.1 after the precipitation tests in all cases. All precipitates were in their respective free forms. The precipitation of ionizable weak acids and bases was slower in BCB than in PPB. The surface pH of precipitating particles may have differed between BCB and PPB due to the slow hydration process of CO2 specific to BCB. Since BCB is a physiological buffer in the small intestine, it should be considered as an option for precipitation studies of ionizable weak acids and bases.

A physiologically-based pharmacokinetic precision dosing approach to manage dasatinib drug-drug interactions.

Dasatinib, a second-generation tyrosine kinase inhibitor, is approved for treating chronic myeloid and acute lymphoblastic leukemia. As a sensitive cytochrome P450 (CYP) 3A4 substrate and weak base with strong pH-sensitive solubility, dasatinib is susceptible to enzyme-mediated drug-drug interactions (DDIs) with CYP3A4 perpetrators and pH-dependent DDIs with acid-reducing agents. This work aimed to develop a whole-body physiologically-based pharmacokinetic (PBPK) model of dasatinib to describe and predict enzyme-mediated and pH-dependent DDIs, to evaluate the impact of strong and moderate CYP3A4 inhibitors and inducers on dasatinib exposure and to support optimized dasatinib dosing. Overall, 63 plasma profiles from perorally administered dasatinib in healthy volunteers and cancer patients were used for model development. The model accurately described and predicted plasma profiles with geometric mean fold errors (GMFEs) for area under the concentration-time curve from the first to the last timepoint of measurement (AUClast) and maximum plasma concentration (Cmax) of 1.27 and 1.29, respectively. Regarding the DDI studies used for model development, all (8/8) predicted AUClast and Cmax ratios were within twofold of observed ratios. Application of the PBPK model for dose adaptations within various DDIs revealed dasatinib dose reductions of 50%-80% for strong and 0%-70% for moderate CYP3A4 inhibitors and a 2.3-3.1-fold increase of the daily dasatinib dose for CYP3A4 inducers to match the exposure of dasatinib administered alone. The developed model can be further employed to personalize dasatinib therapy, thereby help coping with clinical challenges resulting from DDIs and patient-related factors, such as elevated gastric pH.

Breaking the Base Barrier: Cu(II)-Mediated C-H Heteroarylation of o-Carboranes with Base-Sensitive Heteroaryl Halides.

While cage C-arylation reactions using strong bases are among the most frequently used transformations in carborane chemistry, there has been no general solution to allow for the use of weak bases in the reaction. Moreover, base-metal-promoted C-H heteroarylation with base-sensitive heteroaryl halides remained elusive. Herein, copper-mediated cage C-H (hetero)arylation has been achieved without the need for strong bases, leading to the facile synthesis of a wide range of C-(hetero)arylated carboranes in good to excellent yields with a broad substrate scope and good functional group compatibility.

Physical quality assessment of selected made in Nigeria synthetic surfactants for surface activity in Bali, Taraba State, Nigeria

The properties of high-quality soap is determined by its cleansing, foam formation, surface tension, emulsion capacity, pH, etc. To produce a generally better product, soap manufacturing companies take these properties into account during production which necessitated the physical assessment properties of some selected made-in-Nigeria synthetic surfactant for surface activity. The samples were evaluated based on tests for saponins, foam formation and stability, emulsion formation/capacity, surface tension, and pH at different concentrations. The percentage of each of the synthetic surfactants (Ariel=DA, Bonus=DB, Good mama=DG, Sunlight=DS and Zip=DZ) concerning foam formation at five minutes and stability after 30 minutes were as follows; DZ(6.7) > DS(6.3) > DG(5.3) > DA(4.2) > DB(4.1) and DZ(2.6) > DG(1.9) > DA(1.1)/DS(1.1) > DB(1.0) in cm, respectively. The study of the emulsion formation/capacity of the different samples at different concentrations in terms of creamy behaviour was observed as DS > DZ > DA > DG > DB. All the samples studied showed a good reduction in surface tension. At 2g and 10g of the different samples, the following results were obtained: DS(2.87), DZ(20.25), DB(21.55), DA(21.65), DG(21.85) Nm-1 and DS(22.45), DZ(22.25), DB(22.45), DA(26.65), DG(22.65) N/m, respectively. The result of the pH values of the different samples varied within the range of 10.80 to 10.91 as moderately weak base with an increase in concentration. Detergents studied conform to the minimum quality examinations but regular assessment check should be carried out by enforcement/regulatory agencies to ensure quality of detergents produced in the country meets the minimum required standard.

Pharmaceutical Compounding in Veterinary Medicine: Suspension of Itraconazole.

Itraconazole is a drug used in veterinary medicine for the treatment of different varieties of dermatophytosis at doses between 3-5 mg/kg/day in cats. Nevertheless, in Spain, it is only available in the market as a 52 mL suspension at 10 mg/mL. The lack of alternative formulations, which provide sufficient formulation to cover the treatment of large animals or allow the treatment of a group of them, can be overcome with compounding. For this purpose, it has to be considered that itraconazole is a weak base, class II compound, according to the Biopharmaceutics Classification System, that can precipitate when reaching the duodenum. The aim of this work is to develop alternative oral formulations of itraconazole for the treatment of dermatophytosis. Several oral compounds of itraconazole were prepared and compared, in terms of dissolution rate, permeability, and stability, in order to provide alternatives to the medicine commercialized. The most promising formulation contained hydroxypropyl methylcellulose and β-cyclodextrin. This combination of excipients was capable of dissolving the same concentration as the reference product and delaying the precipitation of itraconazole upon leaving the stomach. Moreover, the intestinal permeability of itraconazole was increased more than two-fold.

Measuring outcomes when odontogenic sinusitis is treated with endoscopic sinus surgery: A systematic review

AbstractAimTo determine outcome measurement when odontogenic sinusitis (ODS) is treated by Endoscopic Sinus Surgery (ESS).Materials and MethodsA PRISMA compliant systematic review using MeSH headings on Pubmed, Ovid and Embase. Inclusion criteria: Adults with odontogenic maxillary sinus disease undergoing ESS. Exclusion criteria: Adolescents, odontogenic disease related to; trauma, neoplasia, tumour resection, palatal cleft or fungal infection, previous sinus surgery, endoscopic surgery not involving the middle meatus.ResultsA total of 1462 papers were identified, 68 eligible for review. No randomised controlled trials were identified. Twenty‐three papers (34%) reported a successful outcome as no disease at endoscopy and reduced sinonasal symptoms; 14 papers (21%) based outcomes on endoscopy, reduced symptoms and resolution of sinus opacification or reduced mucosal thickness; 1 paper established success on reduced symptoms only and 7 papers (10%) based outcomes on radiographic findings only. Other primary measures of success were excision and closure of oro‐antral fistula, 6 (9%), removal of odontogenic cysts, 5 (7%), removal of displaced dental implants, 4 (6%), removal of displaced root of tooth, 3 (4%). Five papers (7%) reported no outcome measure. Additional measures of outcome were; retention of dental implants perforating the sinus floor, survival of sinus floor grafting with subsequent implant placement and retention of teeth with persistent apical periodontitis.ConclusionReported outcome measures were very heterogeneous. In consideration of the weak evidence base for the role of ESS in ODS management, more consistent measurement and reporting of patient symptoms, clinical and radiological signs with endoscopic findings is recommended to enable meta‐analysis.

The Effect of Synthetic and Commercial Nano-Magnetite on the Electromagnetic Absorbance Behavior of Magnetic Wood

Magnetic wood with good electromagnetic wave absorption properties was prepared by comparing synthetic and commercial nano-magnetite (Fe3O4-NP) as sengon (Falcataria moluccana) wood impregnation solution. The co-precipitation method produced a synthetic nano-magnetite with NH4OH as a weak base precursor. Meanwhile, the commercial one was purchased from a supplier. Three levels of nano-magnetite concentration (1%, 2.5%, and 5%) were dispersed in deionized water. The impregnation process was done by applying a vacuum of 0.5 bar for 120 minutes, followed by a pressure of 1 bar for 120 minutes. The results showed that the commercial nano-magnetite caused more improvements in weight percent gain, density, and hardness than the synthetic nano-magnetic, although they were insignificantly different. There was also a reduction in brightness with the overall color change being categorized into other colors because the color became darker with increasing nano-magnetite concentration in both woods. The absorbance capacity of the synthetic nano-magnetite-treated wood was larger than the commercial nano-magnetite-treated wood. This synthetic nano-magnetite-treated wood had been optimally treated at a 5% concentration, making it suitable for use as electromagnetic wave shielding material because it can absorb almost 100% electromagnetic waves. Keywords: Fe3O4, impregnation, nano-magnetite, sengon wood, shielding materials

Rapid Sample Pretreatment Facilitating SERS Detection of Trace Weak Organic Acids/Bases in Simple Matrices.

Surface-enhanced Raman spectroscopy (SERS) is a powerful tool for highly sensitive qualitative and quantitative analyses of trace targets. However, sensitive SERS detection can only be facilitated with a suitable sample pretreatment in fields related to trace amounts for food safety and clinical diagnosis. Currently, the sample pretreatment for SERS detection is normally borrowed and improved from the ones in the lab, which yields a high recovery but is tedious and time-consuming. Rapid detection of trace targets in a complex environment is still a considerable issue for SERS detection. Herein, we proposed a liquid-liquid extraction method coupled with a back-extraction method for sample pretreatment based on the pH-sensitive reversible phase transition of the weak organic acids and bases, where the lowest detectable concentrations were identical before and after the pretreatment process. The sensitive (μg L-1 level) and rapid (within 5 min) SERS detection of either koumine, a weak base, or celastrol, a weak acid, was demonstrated in different drinking water samples and beverages. Furthermore, target generality was demonstrated for a variety of weak acids and bases (2 < pKa < 12), and the hydrophilicity/hydrophobicity of the target determines the pretreatment efficiency. Therefore, the LLE-BE coupled SERS was developed as an easy, rapid, and low-cost tool for the trace detection of the two types of targets in simple matrices, which paved the way toward trace targets in complex matrices.

The effect of the impact of the transport load on the strength and deformability of the soil base of the road structure

The article presents the results of determining the strength and deformation characteristics of the soils of the roadbed. Models of road structures located on a weak soil base are also considered, with the justification of design schemes reflecting the basic physical conditions of the structure. The strength of weak soils under the influence of vibration loads depends on their variety and porosity. The higher the density of the soil, the higher its dynamic stability and the greater the values of vibration accelerations, which cause a decrease in its strength. When comparing the calculated data of the dynamic deflection of a weak soil base with experimental data, it was found that the discrepancy in quantitative values does not exceed 10 %, which is quite acceptable for this kind of research. The results obtained and the accepted models of road structures are recommended to be used in calculations of the stability of embankment slopes of the roadbed, as well as in calculations of the precipitation of the embankment body on weak foundations.

Mechanistic Modeling of In Vitro Biopharmaceutic Data for a Weak Acid Drug: A Pathway Towards Deriving Fundamental Parameters for Physiologically Based Biopharmaceutic Modeling.

Mechanistic modeling of in vitro experiments using metabolic enzyme systems enables the extrapolation of metabolic clearance for in vitro-in vivo predictions. This is particularly important for successful clearance predictions using physiologically based pharmacokinetic (PBPK) modeling. The concept of mechanistic modeling can also be extended to biopharmaceutics, where in vitro data is used to predict the in vivo pharmacokinetic profile of the drug. This approach further allows for the identification of parameters that are critical for oral drug absorption in vivo. However, the routine use of this analysis approach has been hindered by the lack of an integrated analysis workflow. The objective of this tutorial is to (1) review processes and parameters contributing to oral drug absorption in increasing levels of complexity, (2) outline a general physiologically based biopharmaceutic modeling workflow for weak acids, and (3) illustrate the outlined concepts via an ibuprofen (i.e., a weak, poorly soluble acid) case example in order to provide practical guidance on how to integrate biopharmaceutic and physiological data to better understand oral drug absorption. In the future, we plan to explore the usefulness of this tutorial/roadmap to inform the development of PBPK models for BCS 2 weak bases, by expanding the stepwise modeling approach to accommodate more intricate scenarios, including the presence of diprotic basic compounds and acidifying agents within the formulation.

Current views on treatment of halitosis: foreign practice

Traditional halitosis treatment involves reducing microbial contamination through chemical and/or mechanical action; however, these methods are ineffective in the long-term.&#x0D; According to recent systematic reviews, there is no scientific evidence of the effectiveness of halitosis treatments, and even when reports indicate a positive effect, it is temporary. To increase the number of studies being compared, analysis of the results of randomized controlled trials (RCTs) should be performed considering already published data. Therefore, a review of recent RCTs is required for conducting and planning further scientific research on halitosis treatment.&#x0D; Purpose of the investigation — to study the effectiveness of oral halitosis treatment based on materials from foreign publications from 2019 to 2023.&#x0D; This article provides a descriptive review of foreign scientific publications on modern methods of treating oral halitosis. A search for full-text articles was conducted in the electronic databases PubMed and Google Scholar for 2019–2023. The most relevant articles that met the selection criteria were selected and included in this review: 31 publications on oral halitosis treatment: 3 Cochrane reviews of RCTs; 14 literature reviews, including meta-analyses; 12 RCTs and clinical studies; and 2 experimental studies.&#x0D; In foreign studies, the use of probiotics and photodynamic therapy and their combination with standard treatment methods are most widely presented; RCTs have established their effectiveness, especially when used together with traditional methods of mechanical tongue cleaning. To prevent halitosis, it appears relevant to use materials with antibacterial properties in prosthetics, particularly the modification of polymethyl methacrylate with silver and graphene nanoparticles.&#x0D; However, against the backdrop of positive results obtained in individual reviews, the conclusions of systematic reviews are contradictory. There is no evidence of the long-term effectiveness of the proposed treatment methods, and there is a weak evidence base for studies, which makes it challenging to use them in the practical work of dentists. In this regard, new RCTs with a longer observation period and considering published data are required.

Enhancing Ensemble Clustering with Adaptive High-Order Topological Weights

Ensemble clustering learns more accurate consensus results from a set of weak base clustering results. This technique is more challenging than other clustering algorithms due to the base clustering result set's randomness and the inaccessibility of data features. Existing ensemble clustering methods rely on the Co-association (CA) matrix quality but lack the capability to handle missing connections in base clustering. Inspired by the neighborhood high-order and topological similarity theories, this paper proposes a topological ensemble model based on high-order information. Specifically, this paper compensates for missing connections by mining neighborhood high-order connection information in the CA matrix and learning optimal connections with adaptive weights. Afterward, the learned excellent connections are embedded into topology learning to capture the topology of the base clustering. Finally, we incorporate adaptive high-order connection representation and topology learning into a unified learning framework. To our knowledge, this is the first ensemble clustering work based on topological similarity and high-order connectivity relations. Extensive experiments on multiple datasets demonstrate the effectiveness of the proposed method. The source code of the proposed approach is available at https://github.com/ltyong/awec.

Total Synthesis of Lobatamides A and C

AbstractThe total synthesis of lobatamides A (1 a) and C (1 c) via a common bislactone intermediate is reported. The allylic aryl moiety including a trisubstituted Z‐olefin was constructed by hydroboration of a 1,1‐disubstituted allene and subsequent Migita‐Kosugi‐Stille coupling. Although the seco acid proved to be highly unstable even in the presence of weak bases, Zhao macrolactonization under acidic conditions via the α‐acyloxyenamide successfully provided the common bislactone intermediate. Hydrozirconation‐iodination of the terminal alkyne and subsequent copper‐mediated coupling with primary amides proceeded successfully in the presence of the sensitive bislactone framework. The developed synthetic route enables the late‐stage installation of enamide side chains, which are crucial structures for V‐ATPase inhibition.

Total Synthesis of Lobatamides A and C.

The total synthesis of lobatamides A (1 a) and C (1 c) via a common bislactone intermediate is reported. The allylic aryl moiety including a trisubstituted Z-olefin was constructed by hydroboration of a 1,1-disubstituted allene and subsequent Migita-Kosugi-Stille coupling. Although the seco acid proved to be highly unstable even in the presence of weak bases, Zhao macrolactonization under acidic conditions via the α-acyloxyenamide successfully provided the common bislactone intermediate. Hydrozirconation-iodination of the terminal alkyne and subsequent copper-mediated coupling with primary amides proceeded successfully in the presence of the sensitive bislactone framework. The developed synthetic route enables the late-stage installation of enamide side chains, which are crucial structures for V-ATPase inhibition.

Exquisite visualization of mitophagy and monitoring the increase of lysosomal micro-viscosity in mitophagy with an unusual pH-independent lysosomal rotor

BackgroundMitophagy plays indispensable roles in maintaining intracellular homeostasis in most eukaryotic cells by selectively eliminating superfluous components or damaged organelles. Thus, the co-operation of mitochondrial probes and lysosomal probes was presented to directly monitor mitophagy in dual colors. Nowadays, most of the lysosomal probes are composed of groups sensitive to pH, such as morpholine, amine and other weak bases. However, the pH in lysosomes would fluctuate in the process of mitophagy, leading to the optical interference. Thus, it is crucial to develop a pH-insensitive probe to overcome this tough problem to achieve exquisite visualization of mitophagy. ResultsIn this study, we rationally prepared a pH-independent lysosome probe to reduce the optical interference in mitophagy, and thus the process of mitophagy could be directly monitored in dual color through cooperation between IVDI and MTR, depending on Förster resonance energy transfer mechanism. IVDI shows remarkable fluorescence enhancement toward the increase of viscosity, and the fluorescence barely changes when pH varies. Due to the sensitivity to viscosity, the probe can visualize micro-viscosity alterations in lysosomes without washing procedures, and it showed better imaging properties than LTR. Thanks to the inertia of IVDI to pH, IVDI can exquisitely monitor mitophagy with MTR by FRET mechanism despite the changes of lysosomal pH in mitophagy, and the reduced fluorescence intensity ratio of green and red channels can indicate the occurrence of mitophagy. Based on the properties mentioned above, the real-time increase of micro-viscosity in lysosomes during mitophagy was exquisitely monitored through employing IVDI. Significance and noveltyCompared with the lysosomal fluorescent probes sensitive to pH, the pH-inert probe could reduce the influence of pH variation during mitophagy to achieve exquisite visualization of mitophagy in real-time. Besides, the probe could monitor the increase of lysosomal micro-viscosity in mitophagy. So, the probe possesses tremendous potential in the visualization of dynamic changes related to lysosomes in various physiological processes.

Experimental and computational insights into the mechanism of destabilization of poly(acrylic acid)-capped silver nanoparticles induced by weak conjugate bases

Herein we report a systematic study of the effects of H2PO4− and ClO4− on the stability of poly(acrylic acid)-capped silver nanoparticles (PAA-AgNPs). Spectroscopic titration revealed that a smaller amount of ClO4− is required to detach PAA, and a blue-shift in surface plasmon resonance (SPR) was observed relative to H2PO4−, owing to its electron accepting nature which leads to a weaking of the PAA-AgNP donor bond. Experimental observations were supported by DFT calculations, which revealed that complexation of AgNPs with ionized PAA, H2PO4– and ClO4− is mediated by the electron affinity of the AgNP and the conjugated bases. Electron donation by the weak acids leads to the weakening of the PAA-AgNP donor bond, whereby ClO4− contributes more to the destabilization of the PAA capped AgNPs due to its greater electron affinity. Additionally, H2PO4− can form hydrogen bonds with PAA, which promotes the formation of aggregates. Moreover, DFT calculations have shown that the structure of the model Ag14 cluster is significantly distorted in the presence of H2PO4−, more so than in the case of ClO4−. The findings are supported by the experimental quantification of residual PAA by differential scanning calorimetry and solid-state total organic carbon analysis (SSM-TOC), and powder X-ray diffraction (XRD).

Drug dialysis through a semipermeable membrane as a preliminary efficacy assessment of a promising parasitocidal drug

The purpose of the research is to analyze the dynamics of fenbendazole (FBZ) and niclozamide (NZM) release from their solid dispersions (SD) of various compositions by dialysis through various semipermeable membranes in model systems that correspond to stomach and intestine environments. To evaluate the parasitocidal activity of experimental mixture compositions.Materials and methods. The study used substances of FBZ and NZM, and the polymer, polyvinylpyrrolidone (PVP). Mechanical processes were carried out in a LE-101 roller mill and an AGO-2 orbital centrifugal mill at different power density levels. The resulting SD of various compositions were studied for solubility. The dynamics of FBZ and NZM substance release from the SD were studied in a laboratory setup consisting of a temperature controlled glass with buffer solutions with pH = 9.18 (intestinal environment) and pH = 1.0 (stomach environment). The substance concentration in the dialysate was determined by HPLC and UV spectroscopy. The resulting complex SD of FBZ and NZM were studied for cestodocidal activity in a laboratory model of hymenolepiosis of white mice.Results and discussion. It was found that the substances release into a buffer solution with pH = 9.18 from the SD obtained in the roller mill is higher than that of the SD obtained in the AGO activator. The dialysis of the experimental compounds in a model system with a gastric juice medium observed only FBZ substance penetration through the membrane, which can be explained by protonation of the FBZ molecule which is a weak base. The NZM molecule, being a neutral molecule, does not penetrate through the semi-permeable partition into the hydrochloric acid environment; it remains entirely inside the dialysis bag. High anthelmintic efficacy rates (up to 100%) of SD complex FBZ : NZM : PVP obtained in the AGO activator and in the roller mill were recorded for the SD of composition 2 : 20 : 78 in the mice with hymenolepiosis. The activity of the base drug, the niclozamide substance, was 27.69%, which is 3 times lower than the activity of the resulting complex dispersions.