Chemical Precipitation Research Papers - Academia.edu (original) (raw)

2025, International Journal of Pharmaceutics

The supercritical antisolvent (SAS) technique was used to prepare ethyl cellulose/methyl cellulose blends, two biocompatible polymers commonly used as drug carriers in controlled delivery systems. Ethyl cellulose is widely used as a drug carrier. The drug release of the delivery devices can be controlled to some extent by addition of a water-soluble or water swellable polymer, such as methyl cellulose. This leads to the solubility enhancement of poorly water-soluble molecules. SAS experiments were carried out at different operational conditions and microspheres with mean diameters ranging from 5 to 30 m were obtained. The effect of CO 2 and liquid flow, temperature and pressure on particle size and particle size distribution was evaluated. The microspheres were precipitated from a mixture of dichloromethane (DCM) and dimethylsulfoxide (DMSO) (4:1 ratio). The best process conditions for this mixture were according to our study 40 • C and 80 bar.

2025, Scientific Investigations Report

2025, Open-file report /

To help water-resource managers evaluate the Floridan aquifer system (FAS) as an alternative water supply, the U.S. Geological Survey initiated a study, in cooperation with the Broward County Environmental Protection and Growth Management Department, to refine the hydrogeologic framework of the FAS in the eastern part of Broward County. This report presents three preliminary cross sections illustrating stratigraphy and hydrogeology in eastern Broward County as well as an interpreted seismic profile along one of the cross sections. Marker horizons were identified using borehole geophysical data and were initially used to perform well-to-well correlation. Core sample data were integrated with the borehole geophysical data to support stratigraphic and hydrogeologic interpretations of marker horizons. Stratigraphic and hydrogeologic units were correlated across the county using borehole geophysical data from multiple wells. Seismic-reflection data were collected along the Hillsboro Canal. Borehole geophysical data were used to identify and correlate hydrogeologic units in the seismicreflection profile. Faults and collapse structures that intersect hydrogeologic units were also identified in the seismic profile. The information provided in the cross sections and the seismic profile is preliminary and subject to revision.

2025, Open-File Report

2025, Scientific Investigations Report

2025, Environmental Science & Technology

The sorption of Pu(VI) onto manganite (MnOOH) and hausmannite (Mn 3 O 4 ) was studied as a function of time, solution pH, and initial plutonium concentration. Kinetic experiments indicate that the surface complexation of plutonium occurs over the first 24 h of contact with the mineral surface. The sorption increases with pH beginning at pH 3 until it reaches a maximum value of 100% at pH 8 (0.0011-0.84 µmol of Pu/m 2 of manganite and 0.98-1.2 µmol of Pu/m 2 of hausmannite) and then decreases over the pH range from 8 to 10. The ratio of solid to solution was 10 mg/mL for manganite experiments and 4 mg/mL for hausmannite samples. Carbonate was not excluded from the experiments. The amount of plutonium removed from the solution by the minerals is determined by a combination of factors including the plutonium solution species, the surface charge of the mineral, and the mineral surface area. X-ray absorption fine structure taken at the Pu L III edge were compared to plutonium standard spectra and showed that Pu(VI) was reduced to Pu(IV) after contact with the minerals. Plutonium sorption to the mineral surface is consistent with an inner-sphere configuration, and no evidence of PuO 2 precipitation is observed. The reduction and complexation of Pu(VI) by manganese minerals has direct implications on possible migration of Pu(VI) species in the environment.

2025, Fluid Phase Equilibria

In the present work, asphaltenes obtained using different n-heptane to crude oil ratios (HCOR) were analyzed using Atmospheric Pressure Photoionization (APPI), and Laser Desorption Ionization (LDI) coupled to Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR MS). The main objective was to improve the understanding of the components of the crude oil that precipitate under different solvent power conditions. Analysis of the compositional distribution of the asphaltenes reveals that the decrease in solvent power produces an increase in DBE and the number of heteroatoms per molecule while the carbon number remains almost unaltered. This finding seems to indicate that one of the main drivers for precipitation is aromaticity as the heptane/crude oil ratio (HCOR) increases and consequently, the solvent power decreases. Both, APPI and LDI FT-ICR MS produce average values that describe the general tendencies obtained using other techniques. Additionally, APPI FT-ICR MS closely match bulk data of the most aromatic asphaltenes obtained in this study.

2025, Dental Materials

Purpose/aim: To evaluate percentile of e.max CAD particle sizes using imaging capabilities after six surface modifications for bonding purposes. Materials and methods: Four crystalized e-max CAD plates (10 × 10 × 1 mm) were sandblasted with aluminum oxide 50 m. Each sample had tapes placed on one of the surfaces dividing it into six equals zones. Each zone then etched

2025, Carbohydrate Polymers

The fructans, inulin and oligofructose, are known to exert many food and pharmaceutical applications and are widely used in functional foods throughout the world for their nutritional and techno-functional properties. In the present study, the Box-Behnken design was used to determine the optimal conditions for fructan precipitation from Eremurus spectabilis root powder (Serish) by adding ethanol that gave the maximum yield. Ethanol-to-syrup (E/S) ratio (2:1-15:1), precipitation temperature (30-60 • C) and syrup concentration (10-40 • B) were considered variables of fructan precipitation. The most compatible model among mean, linear and quadratic expressions was fitted to each response and the regression coefficients were determined using least square method. There was a good agreement between the experimental data and their predicted counterparts. The optimum conditions for fractionating fructan composition of Serish by ethanol were estimated to be E/S ratio of 8.56, temperature of 23.51 • C and initial syrup concentration of 40 • B. Precipitation under these optimized conditions achieved the best yield (85.81%), average chain length (12.92) and purity (80.18%). In addition, principal component analysis (PCA) allowed discriminating among precipitated fructan specialties.

2025, The Journal of Chemical Thermodynamics

2025, Materials Today: Proceedings

Currently, wastewater treatment is one of the most important issues related to the toxic effects of the pathogens and hazardous water pollution impact on human beings, agriculture and animals. In this study, we synthesized copolymer resin by polycondensation method involving 2,4-dihydroxy benzoic acid, -phenyl hydrazine -formaldehyde and activated charcoal. The synthesized copolymer and its composite have been characterized by physico-chemical studies, elemental and spectral analysis. The surface morphology of the adsorbent resins were investigated by scanning electron microscopy (SEM). A detailed analysis of recovery of selected toxic and heavy metal ions (Cu 2+ , Ni 2+ , Co 2+ , Zn 2+ , Pb 2+ ) by the copolymer and composite was carried out by batch separation method. The results revealed that the composite showed better results which may be due to the particle size, high porous nature and larger surface area. The results were compared with earlier reported and commercially available resins and found that the metal ion recovered by the reported synthetic adsorbents was quite remarkable to commercial phenolic and polystyrene resins. The adsorbents could also be successfully reused for several cycles of ionexchange process.

2025, International Journal of Applied and Natural Sciences

The pollution of water bodies with heavy metals presents a significant threat to both the environment and human health because of their harmful, long-lasting, and bioaccumulating properties. As industrialization continues to grow alongside stricter environmental regulations, there is an increasing need for effective and sustainable treatment solutions. This review thoroughly investigates both traditional and advanced techniques for the removal of heavy metals from water and wastewater, including chemical precipitation, adsorption, membrane filtration, electrodialysis, ion exchange, electrochemical methods, ion flotation, and photocatalysis. Each method is carefully analyzed regarding its mechanism, effectiveness in removal, operational requirements, advantages, and drawbacks. Adsorption and membrane-based technologies are noted for their high efficiency and adaptability, particularly when employing low-cost or nano-enabled materials. Chemical precipitation and coagulation-flocculation remain effective for treating high-concentration wastewater, while ion exchange is especially appropriate for the removal of trace amounts of metals. New techniques such as photocatalysis and electrochemical solutions present promising options but encounter challenges concerning scalability and cost. The review highlights that no single approach is the best fit for every situation; instead, the choice of method should consider factors like wastewater composition, metal concentration, environmental impact, and economic viability. By summarizing current research, this paper offers a critical evaluation of existing methods and identifies potential future innovations in heavy metal remediation, stressing the importance of developing eco-friendly, cost-effective, and scalable solutions to protect water resources.

2025, Journal of Virology

A proteolytic activity is associated with structural protein p15 in avian RNA tumor viruses. Its effect on the known intracellular viral polyprotein precursors obtained by immunoprecipitation was investigated. Cleavage of Pr76gag resulted in the sequential appearance of p15, p27, and p19. The intracellular precursor Pr180gag-pol was also cleaved by p15, whereas the intracellular glycoprotein precursors of avian RNA tumor viruses, Pr92env, remained unaffected by p15 under all conditions tested. The specificities of the antibodies used to precipitate the precursors influenced the pattern of intermediates and cleavage products obtained by p15 treatment. If virus harvested from the the Prague strain of Rous sarcoma virus, subgroup C-transformed cells at 15-min intervals was incubated at 37 degrees C for further maturation, RNA-dependent DNA polymerase activity showed an optimum of DNA synthesis with 70S viral RNA or synthetic template-primers after short incubation periods. The presence...

2025, Collegium antropologicum

Physico-chemical investigation of urolithiasis today is mostly focused on applying physico-chemical description of precipitation processes to the stone formation with the aim to distinguish between stone formers and nonstone formers. This is done by calculating supersaturation for different solid phases which can be formed in urine using data obtained by urine analysis and existing solubility product, dissociation and complexation constants. In order for this approach to succeed it is of utmost importance that system is described as detailed as possible, i.e., that all species that can be formed are taken into account. Magnesium hydrogenurate octahydrate, Mg(C5H3N4O3)28H2O (Mg(HU)2.8H2O), is among species which can precipitate in the urine and for which solubility data doesn't exist. In order to fill this void crystals of Mg(C5H3N4O)2.8H2O phase I and phase II have been prepared and characterized. Solubility product constant of Mg(C5H3N4O3)2.8H2O phase I in water at 37 degrees C...

2025, Chemie Ingenieur Technik

2025, Experimental Cell Research

In order to complete preliminary investigations on the subcellular calcium localisation in smooth muscle cells, further experiments are presented using smooth muscle cells from the coronary artery of the pig. The methods used were a precipitation technique using potassium oxalate and autoradiography using 4GCa. In all cases we were able to reproduce the results obtained in our preliminary study. The preparations clearly show calcium oxalate precipitates in the cell membrane, the sarcoplasmic reticulum, the microvesicles, mitochondria and the nucleus membrane. These findings were supported by silver grain distributions in autoradiograms obtained by means of *Wa. The qualitative results obtained histochemically are in good agreement with estimations of the calcium distribution in subcellular fractions obtained by atomic absorption spectrophotometry.

2025, Journal of Hazardous Materials

Magnesium ammonium phosphate hexahydrate (MgNH 4 PO 4 •6H 2 O, MAP) precipitation was studied on up-flow anaerobic sludge blanket (UASB) pretreated poultry manure wastewater in a lab-scale batch study. To recover high strength of ammonium nitrogen (NH 4 + -N = 1318 mg/L) from UASB effluent, three combinations of chemicals including MgCl 2 •6H 2 O + KH 2 PO 4 , MgSO 4 •7H 2 O + NaHPO 4 •7H 2 O, and MgO + 85% H 3 PO 4 were first applied at the stoichiometric ratio (Mg 2+ :NH 4 + -N:PO 4 3--P = 1:1:1) and at different pH levels ranging from 4.45 to 11. Preliminary test results indicated that maximum NH 4 + -N removal, as well as maximum chemical oxygen demand (COD) and color reductions, were obtained as 85.4%, 53.3% and 49.8% at pH 9.0 with the addition of MgCl 2 •6H 2 O + KH 2 PO 4 , respectively. The paired experimental data obtained from batch studies were statistically evaluated by a non-parametric Mann-Whitney test and a two-sample t-test. Based on the previous results, another batch experiments were then performed at pH 9.0 using MgCl 2 •6H 2 O + KH 2 PO 4 for different molar ratios applied as overdose (1

2025, Journal of Experimental Medicine

2025, Biochemistry

Some, but not all, of the aminoacyl-tRNA synthetases present in lysates of rabbit reticulocytes are recovered in high proportion with ribosomes collected by high-speed centrifugation. Up to 90% of the phenylalanyl-tRNA synthetase activity in the lysate is recovered in the ribosomal fraction and appears to have been physically bound to the ribosomes in intact cells. Synthetase activity for lysine and arginine is bound to the ribosome but also appears as a high W e have reported previously the existence of a factor in the salt-wash fraction from reticulocyte ribosomes which promotes binding of N-AcPhe-tRNA or Phe-tRNA to nitrocellulose filters or to ribosomes (McKeehan et al., 1970). This factor was identified as Phe-tRNA synthetase on the basis of cochromatography of the activity for binding and the synthesis of Phe-tRNA plus the specific inhibitory effect of phenylalanine and ATP on N-AcPhe-tRNA binding. It was concluded that a phenylalanyl adenylate complex was formed on Phe-tRNA synthetase bound to ribosomes. Here, we extend these studies and demonstrate an interaction of other synthetases with ribosomes. Materiafs. CHEMICALS. All labeled amino acids were obtained from New England Nuclear, except for cysteine and tryptophan obtained from Amersham-Searle Co. Sephadex G-200 was purchased from Pharmacia. SOLUTIONS. Solution A contained 2 mM Tris.HC1, pH 7.5, 1 mM P-mercaptoethanol, 1 mM EDTA, and 5 % glycerol (v/v). Solution B contained 20 mM Tris.HC1, pH 7.5, 1 mM P-mercaptoethanol, 0.1 mM EDTA, and 0.25 M sucrose. Solution C contained 20 mM Tris . HCl, pH 7.5, 5 mM MgC12,

2025, Journal of Bacteriology

2025, Journal of Pharmacy and Pharmacology

Objectives To investigate the feasibility of using an in-vitro model to simulate the incidence of post-injection drug precipitation (PDP), and to identify the roles of drug properties and delivery systems in its occurrence. Methods A literature review on incomplete absorption following extravascular injection (subcutaneous and intramuscular) was conducted. Six model drugs in nine different formulations were studied for an in-vitro/in-vivo correlation. A rapid in-vitro dilution method using a 96-well plate was used for predicting PDP by dilution with a physiological buffer. New formulations based on hydroxypropyl-β-cyclodextrin (CD), with and without co-solvents or pH control, were developed and tested on the in-vitro model. Key findings The occurrence of precipitation detected from the in-vitro dilution model appeared to be correlated with clinical reports and animal studies. The formulation components played an important role in determining the potential for drug precipitation on d...

2025, Journal of Materials Science: Materials in Medicine

Powders of magnesium-modified as well as zinc-modified calcium phosphates (Me-b-TCP and HA) with a (Ca 2? ?Mg 2? ?Zn 2? ?Na ? ?K ? )/P ratio of 1.3-1.4 and various Me 2? /(Me 2? ?Ca 2? ) ratios (from 0.005 to 0.16) were prepared in biomimetic electrolyte systems at pH 8, mother liquid maturation and further syntering at 600-1000°C. Some differences in zinc and magnesium modifications have been prognosed on the basis of thermodynamic modeling of the studied systems and explained by the Mg 2? and Zn 2? ion chemical behaviour. The temperature as well as the degree of Zn 2? and Mg 2? ions substitutions were found to stabilize the b-TCP structure and this effect was more prononced for zinc. Thus, zincmodified b-TCP powders consisting of idiomorphic crystals were obtained through sintering of Zn 2? ion substituted calcium phosphates precursors at 800-1000°C. The Mg 2? ion substitution leads to obtaining magnesium-modified b-TCP with spherical grains.

2025, Environmental Science & Technology

The ability of Pseudomonas stutzeri strain DCP-Ps1 to drive CaCO 3 biomineralization has been investigated in a microfluidic flowcell (i.e., micromodel) that simulates subsurface porous media. Results indicate that CaCO 3 precipitation occurs during NO 3 -reduction with a maximum saturation index (SI calcite ) of ∼1.56, but not when NO 3 -was removed, inactive biomass remained, and pH and alkalinity were adjusted to SI calcite ∼ 1.56. CaCO 3 precipitation was promoted by metabolically active cultures of strain DCP-Ps1, which at similar values of SI calcite , have a more negative surface charge than inactive strain DCP-Ps1. A two-stage NO 3 -reduction (NO 3 -→ NO 2 -→ N 2 ) pore-scale reactive transport model was used to evaluate denitrification kinetics, which was observed in the micromodel as upper (NO 3 -reduction) and lower (NO 2 reduction) horizontal zones of biomass growth with CaCO 3 precipitation exclusively in the lower zone. Model results are consistent with two biomass growth regions and indicate that precipitation occurred in the lower zone because the largest increase in pH and alkalinity is associated with NO 2 -reduction. CaCO 3 precipitates typically occupied the entire vertical depth of pores and impacted porosity, permeability, and flow. This study provides a framework for incorporating microbial activity in biogeochemistry models, which often base biomineralization only on SI (caused by biotic or abiotic reactions) and, thereby, underpredict the extent of this complex process. These results have wide-ranging implications for understanding reactive transport in relevance to groundwater remediation, CO 2 sequestration, and enhanced oil recovery.

2025, Environmental Science & Technology

2025, Biotechnology Progress

Microbial oxidation of ferrous iron may be a viable alternative method of producing ferric sulfate, which is a reagent used for removal of H2S from biogas. The paper introduces a kinetic study of the biological oxidation of ferrous iron by Thiobacillus ferrooxidansimmobilized on biomass support particles (BSP) composed of polyurethane foam. On the basis of the data obtained, a mathematical model for the bioreactor was subsequently developed. In the model described here, the microorganisms adhere by reversible physical adsorption to the ferric precipitates that are formed on the BSP. The model can also be considered as an expression for the erosion of microorganisms immobilized due to the agitation of the medium by aeration.

2025, Digest Journal of …

Here we reported the synthesis of silver nanoparticles by previously unexploited fungus Hormoconis resinae. On treatment of aqueous solutions of silver with fungus, silver nanoparticles could be rapidly fabricated within an hour. These nanoparticles were characterized with UV-Vis spectroscopy, XRD, TEM and EDX analysis which revealed that the silver nanoparticles are polydisperse and of different morphologies ranging from 20 to 80 nm in size. X-ray diffraction (XRD) results reveal that these nanostructures exhibit a face-centered cubic crystal structure. To the best of our knowledge, this is the first report of silver nanoparticles synthesis using fungus Hormoconis resinae.

2025, The Journal of Immunology

Lymphocyte activation entails a sequence of events identified by analyzing the time course of expression of various distinctive cell surface molecules on lymphocytes that appear early (before initiation of DNA synthesis), parallel with DNA synthesis and cellular proliferation, or late (after peak proliferation). In this study we present identification of a novel late lymphocyte activation antigen, Act I, utilizing a murine monoclonal antibody. Anti-Act I was identified in a fusion of NS1 with BALB/c spleen cells immunized with a human tetanus toxoid-reactive T lymphoblast line. Flow cytometry analysis shows that Act I antigen is present in markedly greater amounts on activated T and B lymphocytes than on resting, small peripheral blood lymphocytes. Act I expression by these lymphocytes is promoted by PHA, tetanus toxoid, or alloantigens and lags behind maximal thymidine incorporation by 1 to 2 days. Thymocytes can be triggered to express Act I antigen during maturation induced by PH...

2025, Water Science and Technology

Laboratory- and pilot-scale studies were conducted in order to adjust and optimize the in-situ conditions for bioremediation of a soil contaminated with trichlororethene (TCE) and nickel. Results from laboratory studies showed that the indigenous microorganisms of the soil were limited by the type of electron donor. A better TCE dechlorination was obtained when the electron donor was composed of a mixture of methanol and lactate, as compared to that with methanol alone. Addition of up to 10 mM of sulphate as external electron acceptor (in combination with TCE) and with a mixture of methanol and lactate as electron donor had no significant effect on the TCE reducing activity of indigenous microorganisms of the soil, while higher concentrations (15 and 20 mM) yielded a lower dechlorination. Long term operation of a large pilot-scale soil reactor demonstrated the feasibility of a single-process in situ soil remediation. Results showed that, on one hand, TCE was progressively and stepwi...

2025

In order to obtain a high yield from animals, improvement studies were carried out by various methods. Until 1990’s, improvement studies were carried out only with phenotypic methods. With the rapid development of genetic science, the possibilities of using genome analysis in improvement studies were investigated. One of the genomic analysis sections is the functional gens. In order to be able to reveal the efficacy of the functional gens, the possibilities of using metabolomics in animal improvement have begun to be investigated. There are nearly 20000 metabolites in living beings. When the relationship of these metabolites with yields, diseases and adaptations of livestock animals is revealed, the use of metabolites in animal improvement is thought to make selection more efficient.

2025

Hayvanlardan yuksek duzeyde verim elde edebilmek icin cesitli yontemlerle islah calismalari uygulanmistir. 1990’li yillara kadar sadece fenotipik yontemlerle islah calismalari yapilmistir. Genetik biliminde hizli gelisimle birlikte islah calismalarinda genom analizlerinin kullanilma olanaklari arastirilmistir. Genomik analiz bolumlerinden birisi islevsel genlerdir. Islevsel genlerin etkinliginin ortaya konabilmesi icin hayvan islahinda metabolitlerin kullanilma imkânlari arastirilmaya baslanmistir. Canlilarda 20.000’e yakin metabolit bulunmaktadir. Bu metabolitlerin ciftlik hayvanlarinin verimleri, hastaliklari ve adaptasyonlariyla ilgili iliskileri ortaya konuldugunda, hayvan islahinda metabolitlerin kullanilmasinin seleksiyonu daha etkin yapacagi dusunulmektedir.

2025

The extraction of metallic nanoparticles (MNPs) from waste electrical and electronic equipment (WEEE) has gained extensive attention from researchers for eco-friendly, reliable, and sustainable alternative protocol over the traditional linear economic approach (make-use-dispose) for boosting the circular economy. A plethora of MNPs including metals/metal oxide nanoparticles having a size dimension ranging from 1-100 nanometers (nm) have been extracted from these WEEE by using different chemical, physical, and biological methods. Recovery of certain precious MNPs can be achieved by dismantling and recycling electronic waste items in the form of gold (Au), platinum (Pt), zinc oxide (ZnO), silver (Ag), and copper oxide (CuO). These MNPs provide a huge range of applications such as antibacterial, therapeutic, target drug delivery, and biotechnological applications. This comprehensive review provides in-depth knowledge of the synthesis of MNPs using different techniques from WEEE and delves into their potential applications in biomedical fields with in-depth mechanisms. This article also discussed global challenges and opportunities in this area for adopting the concept of circular economy to conserve natural resources for future generations and hence create a greener environment and protect our planet.

2025, Journal of Histochemistry & Cytochemistry

Phenanthrenequinone, in an alkaline ethanolic solution, is shown to be specific for the guanidino group of arginine in tissues. The fluorescence measured in chick erythrocyte nuclei is highly reproducible among areas on one slide and among different slides. Benzil and cyclohexanedione, two agents known to be specific for the guanidino group, prevent 85% of the fluorescence developed in the phenanthrenequinone reaction. Glyoxal blocks phenanthrenequinone reactivity only partially, while alkaline formaldehyde has little effect. The effects of fixation and postfixation of chick erythrocyte nuclei indicate that fluorescence is most intense after formalin fixation, and that conformational factors may prevent ethanolacetic acid-fixed nuclei from reacting completely. By means of protein precipitation and prolonged incubation in ethanol, it was shown that the fluorescent chromophore is strongly bound to phenanthrenequinone-reacted gelatin and to tissue sections. Excitation and emission spec...

2025, International Journal of Molecular Sciences

We report on a recycling project in which α-Al 2 O 3 was produced from aluminum cans because no such work has been reported in literature. Heated aluminum cans were mixed with 8.0 M of H 2 SO 4 solution to form an Al 2 (SO 4 ) 3 solution. The Al 2 (SO 4 ) 3 salt was contained in a white semi-liquid solution with excess H 2 SO 4 ; some unreacted aluminum pieces were also present. The solution was filtered and mixed with ethanol in a ratio of 2:3, to form a white solid of Al 2 (SO 4 ) 3 •18H 2 O. The Al 2 (SO 4 ) 3 •18H 2 O was calcined in an electrical furnace for 3 h at temperatures of 400-1400 °C. The heating and cooling rates were 10 °C /min. XRD was used to investigate the phase changes at different temperatures and XRF was used to determine the elemental composition in the alumina produced. A series of different alumina compositions, made by repeated dehydration and desulfonation of the Al 2 (SO 4 ) 3 •18H 2 O, is reported. All transitional alumina phases produced at low temperatures were converted to α-Al 2 O 3 at high temperatures. The X-ray diffraction results indicated that the α-Al 2 O 3 phase was realized when the calcination temperature was at 1200 °C or higher.

2025, Aaps Journal

Our knowledge of the major mechanisms underlying the effect of food on drug absorption allows reliable qualitative prediction based on biopharmaceutical properties, which can be assessed during the pre-clinical phase of drug discovery. Furthermore, several recent examples have shown that physiologically based absorption models incorporating biorelevant drug solubility measurements can provide quite accurate quantitative prediction of food effect. However, many molecules currently in development have distinctly sub-optimal biopharmaceutical properties, making the quantitative prediction of food effect for different formulations from in vitro data very challenging. If such drugs reach clinical development and show undesirable variability when dosed with food, improved formulation can help to reduce the food effect and carefully designed in vivo studies in dogs can be a useful guide to clinical formulation development. Even so, such in vivo studies provide limited throughput for screening, and food effects seen in dog cannot always be directly translated to human. This paper describes how physiologically based absorption modeling can play a role in the prediction of food effect by integrating the data generated during pre-clinical and clinical research and development. Such data include physicochemical and in vitro drug properties, biorelevant solubility and dissolution, and in vivo pre-clinical and clinical pharmacokinetic data. Some background to current physiological absorption models of human and dog is given, and refinements to models of in vivo drug solubility and dissolution are described. These are illustrated with examples using GastroPlus™ to simulate the food effect in dog and human for different formulations of two marketed drugs.

2025, Acta pharmaceutica (Zagreb, Croatia)

The main objective of this study was to synthesize hydroxyapatite-ciprofloxacin composites using a chemical precipitation method and to evaluate the properties and in vitro release profile of the drug from the hydroxyapatite-ciprofloxacin composites. Composite characterization was achieved by FT-IR, XRD and DLS. Ciprofloxacin determination was accomplished by HPLC, resulting in good incorporation efficiency of the drug (18.13 %). The in vitro release study (Higuchi model C = K t1/2 and Ritger-Peppas model, C = K t0.6) showed a diffusion-controlled mechanism. The antibacterial activity showed that the bacterial growth inhibition zones were approximately equal for the synthesis composites and for the mechanical mixture on the Staphylococcus aureus germ. The use of hydroxyapatite, which is a biocompatible, bioactive and osteoconductive material, with ciprofloxacin, which has good antibacterial activity in this composite, makes it suitable for the development of bone grafts. Furthermore...

2025, Journal of Eukaryotic Microbiology

Biological soil crusts are diverse assemblages of bacteria, cyanobacteria, algae, fungi, lichens, and mosses that cover much of arid land soils. The objective of this study was to quantify protozoa associated with biological soil crusts and test the response of protozoa to increased temperature and precipitation as is predicted by some global climate models. Protozoa were more abundant when associated with cyanobacteria/lichen crusts than with cyanobacteria crusts alone. Amoebae, flagellates, and ciliates originating from the Colorado Plateau desert (cool desert, primarily winter precipitation) declined 50-, 10-, and 100-fold, respectively, when moved in field mesocosms to the Chihuahuan Desert (hot desert, primarily summer rain). However, this was not observed in protozoa collected from the Chihuahuan Desert and moved to the Sonoran desert (hot desert, also summer rain, but warmer than Chihuahuan Desert). Protozoa in culture began to encyst at 37 1C. Cysts survived the upper end of daily temperatures (37-55 1C), and could be stimulated to excyst if temperatures were reduced to 15 1C or lower. Results from this study suggest that cool desert protozoa are influenced negatively by increased summer precipitation during excessive summer temperatures, and that desert protozoa may be adapted to a specific desert's temperature and precipitation regime.

2025, The Journal of Eukaryotic Microbiology

2025

The copyright of this thesis vests in the author. No quotation from it or information derived from it is to be published without full acknowledgement of the source. The thesis is to be used for private study or noncommercial research purposes only. Published by the University of Cape Town (UCT) in terms of the non-exclusive license granted to UCT by the author. staff (past and present) in the Department for the many analyses they helped with. Miranda Waldron from Electron Microscopy Unit at UCT for all the micro-structural analysis. All my fellow postgraduate colleagues and support stuff (past and present) in the Crystallization and Precipitation Unit and the Department of Chemical Engineering. Their support and encouragement kept me going when times where tough. Ms Fran Pocock for always been available to lend an ear when I needed to offload. My parents, sisters, nephews and nieces for all their love, understanding, patience and support. My beautiful fiancée (Malebo), Palesa and Mokhethoa for always putting a smile on my face and standing by me. I appreciate all the sacrifices they made to help me realise this dream. I would especially like to thank my family as a whole and friends for always believing in me and my dreams.

2025, PLoS ONE

Background and Aims: Unnatural self-organizing biomimetic polymers (foldamers) emerged as promising materials for biomolecule recognition and inhibition. Our goal was to construct multivalent foldamer-dendrimer conjugates which wrap the synaptotoxic b-amyloid (Ab) oligomers with high affinity through their helical foldamer tentacles. Oligomeric Ab species play pivotal role in Alzheimer's disease, therefore recognition and direct inhibition of this undruggable target is a great current challenge. Methods and Results: Short helical b-peptide foldamers with designed secondary structures and side chain chemistry patterns were applied as potential recognition segments and their binding to the target was tested with NMR methods (saturation transfer difference and transferred-nuclear Overhauser effect). Helices exhibiting binding in the mM region were coupled to a tetravalent G0-PAMAM dendrimer. In vitro biophysical (isothermal titration calorimetry, dynamic light scattering, transmission electron microscopy and size-exclusion chromatography) and biochemical tests (ELISA and dot blot) indicated the tight binding between the foldamer conjugates and the Ab oligomers. Moreover, a selective low nM interaction with the low molecular weight fraction of the Ab oligomers was found. Ex vivo electrophysiological experiments revealed that the new material rescues the long-term potentiation from the toxic Ab oligomers in mouse hippocampal slices at submicromolar concentration. The combination of the foldamer methodology, the fragment-based approach and the multivalent design offers a pathway to unnatural protein mimetics that are capable of specific molecular recognition, and has already resulted in an inhibitor for an extremely difficult target.

2025, Biotechnology Progress

Genetically engineered versions of β‐galactosidase were constructed through the addition of charged polypeptide fusion tails for the purpose of enhancing polyelectrolyte precipitation. Negatively charged aspartic acid tails and positively charged poly(arginine) tails were added to β‐galactosidase from Escherichia coli. These fusion proteins were all shown to possess specific activity equal to that of the native enzyme. Gel permeation and ion‐exchange chromatography provided evidence concerning the integrity of the tails as well as their altered charge characteristics. All enzymes containing charged tails displayed enhanced polyelectrolyte precipitation over the native enzyme. An optimal number of charged residues, beyond which no further enhancement of precipitation was observed, was found to be approximately 10 residues for each type of tail. No interference from nucleic acids was observed in the precipitation of positively tailed β‐galactosidase.

2025, Microbial Pathogenesis

2025, FEBS Letters

The thioredoxin-catalyzed insulin reduction by dihydrolipoate was applied to study the 2-oxoacid:lipoate oxidoreductase activity of 2-oxoacid dehydrogenase complexes. The enzymatic and non-enzymatic mechanisms of the transfer of reducing equivalents from the complexes to free lipoic acid (a-lipoic acid, 6,8-thiooctic acid) were distinguished using the high stereoselectivity of the complex enzymes to the R-enantiomer of lipoate. Unlike these enzymes, thioredoxin from E. coli exibited no stereoselectivity upon reduction with chemically obtained dihydrolipoate. However, coupled to the dihydrolipoate production by the dehydrogenase complexes, the process was essentially sensitive both to the enantiomer used and the dihydrolipoyl dehydrogenase activity of the complexes. These results indicated the involvement of the third complex component, dihydrolipoyl dehydrogenase, in the 2-oxoacid-dependent dihydrolipoate formation. The implication of the investigated reaction for a connection between thioredoxin and the 2-oxoacid dehydrogenase complexes in the mitochondrial metabolism are discussed.

2025, Nucleic Acids Research

Procedures which allow the rapid extraction of small amounts of phage DNA in a sufficiently pure form as to be digested with restriction enzymes are an important tool in the analysis of recombinant clones. This communication describes an alternative procedure to the current method of polyethylene glycol (PEG) sedimentation followed by phenol extractions (1), which is based on the precipitating action of zinc chloride (ZnCl2). Precipitation by ZnCl2 has first been observed in experiments with B.subtilis phage SPPl. Suspensions of SPPl in LB

2025, Applied microbiology and biotechnology

There have been extensive and comprehensive reviews in the field of metal sulfide precipitation in the context of environmental remediation. However, these works have focused mainly on the removal of metals from aqueous solutions-usually, metal-contaminated effluents-with less emphasis on the precipitation process and on the end-products, frequently centering on metal removal efficiencies. Recently, there has been an increasing interest not only in the possible beneficial effects of these bioremediation strategies for metal-rich effluents but also on the formed precipitates. These metal sulfide materials are of special relevance in industry, due to their optical, electronic, and mechanical properties. Hence, identifying new routes for synthesizing these materials, as well as developing methodologies allowing for the control of the shape and size of particulates, is of environmental, economic, and practical importance. Multiple studies have shown proof-of-concept for the biological s...

2025, Journal of Histochemistry & Cytochemistry

Purified rabbit antiserum to a tartrate-resistant and vanadate-sensitive acid phosphatase (nucleotide tri- and diphosphatase) prepared from rat bone was used in immunocytochemical studies. The antigen was localized in sections of fixed, decalcified tissue (head from rat) using the peroxidase-antiperoxidase bridge (PAP) or the avidin-biotin-peroxidase complex (ABC) technique. Both techniques resulted in similar and specific immunostaining in the following cells and tissues: osteoclasts situated in resorption lacunae, epithelium overlying enamel-free areas of tips of cusps of unerupted molars, cilia of respiratory epithelium, and tissue macrophages. This distribution corresponds to the cellular sites of tartrate-resistant acid phosphatase activity, as revealed by enzyme histochemistry. With the ABC method, staining in osteoclasts was obtained with antiserum dilutions of up to 1:10,000. Biochemical studies revealed that vanadate-sensitive acid ATPase activity in liver subcellular fract...

2025, Chemosphere

Although it has already been shown that calcareous stone can be consolidated by using a bacterially-inoculated culture media, a more user-friendly method is the in situ application of a sterile culture media that is able to activate, among the microbial community of the stone, those bacteria with a potential for calcium carbonate precipitation. In order to test this new method for stone consolidation, non-sterilized decayed porous limestone was immersed in sterile nutritional media. Results were compared to those of the runs in which stone sterilized prior to the treatment was used. The effects of the microbial community on stone consolidation were determined by recording the evolution of the culture media chemistry. The treated stone was tested for mechanical resistance and porosity. Results demonstrate that the tested media were able to activate bacteria from the microbial community of the stone. As a consequence of the growth of these bacteria, an alkalinization occurred that resulted in calcium carbonate precipitation. The new precipitate was compatible with the substrate and consolidated the stone without pore plugging. Therefore, a good candidate to in situ consolidate decayed porous limestone is the application of a sterile culture media with the characteristics specified in the present study.

2025

Laboratory-scale characterizations of the mixing zone for reactive transport in a carbonate system.

2025, Journal of Proteome Research