Thermal Precipitation Research Articles

DISTRIBUTION OF NATURAL RADIONUCLIDES IN ASHES, COLLECTED BY THERMAL POWER PLANTS ELECTROSTATIC PRECIPITATOR

Link for citation: Nazirov R.A., Vede P.Yu., Tarasov I.V., Zhuikov A.V., Sergunicheva E.M., Tolochko O.R. Distribution of natural radionuclides in ashes, collected by thermal power plants electrostatic precipitator. Bulletin of the Tomsk Polytechnic University. Geo Аssets Engineering, 2023, vol. 334, no. 7, рр. 177-186. In Rus. Relevance. In the context of the global trend towards sustainable development, there is a problem of utilization of ash and slag waste from thermal power plants. The use of these wastes in the construction industry is of particular importance, due to the resource intensity of the production of building materials. Fly ash in the building materials composition can influence to a large extent the natural radioactivity of structures and increase the background radiation in the buildings. This is due to the fact that when coal combusting, fly ash is enriched with natural radionuclides. Purpose: to study the radioactivity of fly ash deposited on various fields of the electrostatic precipitator. Object: fly ash deposited on the fields of electrostatic precipitators from the combustion of Kansk-Achinsk brown coal in power boilers BKZ-420-140 PT-2. Methods. Content of Ra-226, Th-232 and K-40 was determined by gamma-spectrometric method, the value of the normalized indicator of specific effective activity for fly ash was calculated. The granulometric composition of the studied samples was determined by the method of laser diffraction analysis. Cluster analysis was used for statistical processing of test results. Results. The presence of two clusters in the content of natural radionuclides was established. In the first cluster, which has high radioactivity, the first and second fields of UGZ-4 electrostatic precipitators are combined, and in the second – the third and fourth fields. A correlation dependence was established between the numbers of fields of electrostatic precipitators, the size of ash particles, the content of Ra-226 and specific effective activity was established. No such dependence was found for Th-232. Conclusions. Particle distribution in the fields of electrostatic precipitators is multimodal. The nature of the distribution of each mode approaches the lognormal law. The content of radium and the value of the specific effective activity depend on the size of ash particles and are described by an exponential function. The highest content of Ra-226 is observed in the ashes deposited on the third and fourth fields of electrostatic precipitators, which indicates the enrichment of finer ash particles with this radionuclide. The conclusions obtained correspond to the well-known thesis about the increased radioactivity of ash particles that are not deposited by ash collection systems and enter the atmosphere together with flue gases. The proposed method for studying the distribution of natural radionuclides over the fields of electrostatic precipitators can be used to predict the radioactivity of particles that are not captured by the flue gas cleaning system and released into the environment.

Atomistic simulation of hardening in bcc iron-based alloys caused by nanoprecipitates

The paper presents results of atomistic simulations of hardening in model bcc iron-based alloys due to secondary phase precipitates formation. The simulations are based on shear stress relaxation technique and experimental data on morphology of precipitates. Atomistic methods were developed to reproduce the shear strength of bcc iron-based materials. The large-scale atomistic simulations were carried out for model binary alloys: Fe–Cr imitating low-carbon ferritic and ferritic–martensitic steels and Fe–Cu imitating low-carbon bainitic steel. A representative set of atomic structures is compiled with account for the chemical composition and concentration and size of secondary phase, comparable with those in steels of the considered classes and available experimental data on radiation and thermal induced precipitation. Obtained results on hardening were verified against experimental data and the dispersed barrier hardening model.

Design and evaluation of a thermal precipitation aerosol electrometer (TPAE)

Abstract. A new aerosol electrometer (AE), the thermal precipitation aerosol electrometer (TPAE), was designed for use with particles of sizes less than 300 nm, and its performance was experimentally evaluated. The TPAE combines the thermal precipitator with a microcurrent measurement circuit board (i.e., pre-amplifier) for measuring the current carried by collected particles. The thermal precipitator is in the disk-to-disk configuration. Heating paste and air cooling were adopted to establish the desired temperature gradient in the precipitation chamber. At a sample flow rate of 0.3 L min−1 and a temperature gradient of 264 K cm−1, the precipitation efficiency of 70 nm particles reaches ∼100 %. The measurement range of the designed aerosol electrometer is ±5×105 fA, and the accuracy is ±2 fA (2500 to 6.25×107 cm−3 using a flow rate of 0.3 L min−1 and assuming that only singly charged particles exist in the sample). During the evaluation process, the electrical performance of the TPAE was first tested using sodium chloride (NaCl) and soot particles previously classified by a differential mobility analyzer (DMA) and compared to the reference. The precipitation performance of the TPAE was then characterized as functions of the temperature gradient, sampling flow rate and particle size. It was shown that the particle collection efficiency of the built-in thermal precipitator is inversely proportional to the sampling flow rate and proportional to the temperature gradient. The effect of particle size on the particle collection efficiency was minor for NaCl particles of sizes between 23 and 200 nm. Unlike that which was observed for the NaCl particles, a slightly positive correlation between the collection efficiency and the mobility size for soot particles (in the size range of 30–160 nm) was observed. This observation might be due to the existence of soot agglomerates. Compared to existing electrometers, the TPAE does not require the use of high-efficiency filters and includes the additional feature of the “soft” collection of particles for offline particle characterization as well as aerosol current measurement.

Leveraging similarity analysis to understand variability in movement behavior

AbstractThe increasingly large volume of trajectories of moving entities obtained through GPS and cellphone tracking, telemetry, and other location‐aware technologies motivates researchers to understand the implicit patterns hidden in movement trajectories and understand how movement is influenced by the environmental context. Trajectory similarity serves as an important tool in computational movement analysis and as the foundation of revealing those patterns. However, there are various trajectory similarity measures, each of which has its own strengths and weaknesses. In this article, we present a hierarchical clustering framework that integrates five commonly used similarity measures, including Fréchet distance, dynamic time warping, Hausdorff distance, longest common subsequence, and normalized weighted edit distance, a special kind of edit distance for movement analysis. The framework aims at clustering similar patterns and identifying variability in movement. The optimal number of clusters are first obtained. Then, the clusters are characterized by environmental variables to explore the associations between variability in movement and the environmental conditions. We evaluate the proposed framework using 15 years of tracking data of turkey vultures, tracked at 1‐ to 3‐h sampling intervals, during their fall and spring migration seasons. The results suggest that, at 5% significance level, turkey vultures select their movement paths intentionally and those selections appear to be related to certain environmental context variables, including thermal uplift, vegetation state (observed indirectly through Normalized Difference Vegetation Index), temperature, precipitation, tailwind, and crosswind. And interestingly, there exist preferential differences among individuals. Although the preference of the same turkey vulture is not strictly consistent over different years, each individual tends to preserve a more similar preference over different years, compared with the preferences of other turkey vultures.

New insights into selective flotation recovery of gold using dye-derived thermo-responsive polymeric surfactant: DFT calculation and adsorption mechanism

The selective flotation recovery of gold from secondary resources is a sustainable strategy to fill the ever-increasing demand for gold resources, and reduce the environmental pollution. In the present work, a novel method to realize the selective and fast recovery of Au(III) in the flotation process involving the use of thermo-responsive amphiphilic polymer poly(ethylene glycol)-b-poly(N-isopropylacrylamide-co-glycidyl methacrylate) (PEG113-b-P(NIPAM108-co-GMA62)) integrated with rhodamine B thiohydrazide (RBS) affinity ligand was studied. The polymer possessed the selective capture property toward Au(III) salt and excellent adsorption performance on bubble surfaces, driven by specific coordination interactions between Au(III) salt and RBS ligand, and hydrophobic interactions between GMA moieties and bubbles. Flotation using the thermo-responsive polymeric surfactant displayed a high separation efficiency and fast flotation kinetics, achieving a separation efficiency of 85% for Au(III) salt at 28 min, which was comparable with sulfur-functionalized mesoporous materials. This flotation process followed pseudo-second-order kinetics and Freundlich isotherm adsorption model. Furthermore, in flotation recovery of Au(III) salt form actual e-waste leaching solution, separation efficiency of 81% was achieved, while Au grade was improved from 1.55 % to 34.76%. This polymeric surfactant was easily regenerated by the reduction-induced release the bound Au(III) salt and thermal precipitation, leading to retain 81% of separation efficiency after five cycles. This work provides an effective way to fabricate flotation surfactant, which can meet the urgent demand for performance improvement and chemical consumption reduction in practical applications.

High temperature effect on short crack behaviour in hypoeutectic Al-Si alloys and its modelling

Hypoeutectic Al-Si alloys used for components facing the combustion chamber of automotive engines necessitate excellent high-temperature mechanical properties. In this study, the effect of high temperature on short crack behaviour of hypoeutectic Al-Si alloys is investigated experimentally. The results show that the short crack growth rate is affected by thermal softening and precipitate coarsening. At 200 °C, the slight thermal softening and the positive effect of short-term precipitate coarsening causes the crack growth rates remain unchanged compared to room temperature (RT). At 250 °C, the crack growth rate remains essentially constant during the early stage, while with increasing testing time, the crack growth rate increases rapidly due to the precipitate coarsening. At 300 °C, the crack growth rate is significantly enhanced due to thermal softening and precipitate coarsening. Due to thermal softening, the elastic modulus and yield stress (σys) decrease with increasing temperature. Due to time and temperature dependent precipitate coarsening, the σys drops sharply with the testing time at 250 °C and 300 °C. At 200 °C, the σys increases first and then decreases with the increase of testing time. The transgranular mode dominates the short crack growth at both RT and high temperatures. The grain boundaries have an apparent suppression effect on crack growth. Finally, the relationships between σys and temperature are established for crack tip opening displacement range (ΔCTOD) calculation. The short crack growth rates can be well characterized and predicted by ΔCTOD.

Revealing the microstructural evolution and its influence on mechanical properties of heterostructured steel fabricated by laser melting deposition

A series of heterostructured materials with variable ratio of 316 powders in 18Ni300 powders were prepared by laser melting deposition (LMD). The microstructural evolution and its influence on tensile features were explored before/after aging treatment or solution-aging treatment. The results indicated that the fraction of γ phase was increased gradually with increasing 316SS, and dislocation caused by the deformation could be migrated and annihilated within the region of γ phase, second phase strengthening could contribute to excellent elongation for 18Ni300 maraging steel. The elongation of the AF4 sample was 235.2% higher than that of the AF0 sample when a 37.5% reduction in the ultimate tensile strength occurred. In addition, thermal stress could exist in the as-cladded sample, an appropriate heat treatment could release the thermal stress and precipitate nanoscale intermetallic compound. Their synergistic effect could contribute to overcoming the strength-elongation trade-off. A relatively ideal sample, a discontinuous γ phase surrounded by α phase, which displayed high strength of 1678.4 MPa with high elongation of 10.9% after solution-aging treatment. Compared with laser cladded 18Ni300 maraging steel, a 41.7% increment in the elongation was obtained at the cost of 11.3% reduction in ultimate tensile strength.

Thermal dynamics assessment of vanadium redox flow batteries and thermal management by active temperature control

Understanding the thermal dynamics of vanadium redox flow batteries (VRFB) is critical in preventing the thermal precipitation of vanadium species that result in capacity fading and unsafe operation. This paper presents a comprehensive thermal model of a 5 kW/60 kWh VRFB system by considering the impact of current, ambient temperature and electrolyte flow rate to investigate the dynamic and steady-state thermal conditions of VRFB systems. To analyse the feasibility of using air conditioners for effective thermal management, a room temperature model is proposed to simulate the room temperature variations with air flow cooling. Finally, based on the proposed VRFB thermal model and the room temperature model, two case studies with different temperature profiles are presented to evaluate the performance of the proposed model. Most importantly, an improved cooling strategy is proposed and validated for the two case studies considering the different thermal behaviours of VRFBs during charging and discharging. The simulation results show that the proposed strategy can save up to 48% on air conditioner consumption. Also, the modelling work presented in this paper is useful for studying the thermal dynamics of a VRFB system after many operational cycles and providing guidance for the thermal management of VRFBs in real-world applications.

Preparation and Thermal hydrolysis chemistry of Thin film from Zinc Oxide (ZnO) and studying of the factor which dependent on

Thin films of Zinc oxide was prepared by using thermal chemical hydrolysis and precipitate on glass base at (450 ). Then Physical properties of the prepared thin films was studied as well as of studying of thickness of this films and the factors which dependent on such as ( Temperature degree, Rate of Spray , The time of Spray, The vertical distance of Spray) ,which need to get films with good properties.

Formation, evolution and remove behavior of manganese-containing inclusions in medium/high manganese steels

The effect of manganese content, aluminium content, top slag and stirring on manganese-containing inclusions characteristics was investigated by laboratory thermal experiments and precipitation thermodynamics calculation. The results indicated that the types of manganese-containing inclusions in manganese steel were mainly single MnS, MnS–Al2O3, MnS–TiN and MnS–Al2O3–TiN complex inclusions. The morphology of manganese-containing inclusions was transformed from spherical and ellipsoidal to polyhedral as result of manganese content increased, which is attributed to large solidus-liquidus phase difference of high manganese steel, promoting the formation of type III MnS. It is also found that the manganese-containing inclusions shows irregular morphology with clear angularities after addition of aluminium, which was determined by both formation of flaky AlN and type III MnS with polygonal caused by increased of activity coefficient of S and the surface tension of molten steel. Furthermore, the manganese-containing inclusions in manganese steel is considered MnS–MnO type with top salg, in which patchy or multipoint shape MnS is embedded on the surface of oxide. The force field analysis in induction stirring demonstrated that the inclusion particles are removed by top slag and refractory adsorption under the action of strong electromagnetic force and buoyancy. This work provides an improved understanding for the controlling and removing of manganese-containing inclusions in high quality medium/high manganese steel.

Preparation of Temperature-Responsive Antibody-Nanoparticles by RAFT-Mediated Grafting from Polymerization.

Herein, we report the preparation of temperature-responsive antibody-nanoparticles by the direct polymerization of N-isopropylacrylamide (NIPAAm) from immunoglobulin G (IgG). To this end, a chain transfer agent (CTA) was introduced into IgG, followed by the precipitation polymerization of NIPAAm in an aqueous medium via reversible addition-fragmentation chain transfer polymerization above the lower critical solution temperature (LCST). Consequently, antibody-polymer particles with diameters of approximately 100-200 nm were formed. Owing to the entanglement of the grafted polymers via partial chemical crosslinking, the antibody-nanoparticles maintained their stability even at temperatures below the LCST. Further, the dispersed nanoparticles could be collected by thermal precipitation above the LCST. Additionally, the antibody-nanoparticles formulation could maintain its binding constant and exhibited a good resistance against enzymatic treatment. Thus, the proposed antibody-nanoparticles can be useful for maximizing the therapeutic potential of antibody-drug conjugates or efficacies of immunoassays and antibody recovery and recycling.

Time-Dependent Stagnation Point Flow of Water Conveying Titanium Dioxide Nanoparticle Aggregation on Rotating Sphere Object Experiencing Thermophoresis Particle Deposition Effects

The notion of thermophoretic particle deposition is used in a number of applications, including thermal exchanger walls. It is important to identify the transport processes in action in systems such as thermal precipitators, exhaust devices, optical transmission fabrication processes, and so on. Based on these application points of view, the present work studies the performance of nanoparticle aggregation stagnation point flow over a rotating sphere during the occurrence of thermophoretic particle deposition. The nonlinear governing equations are transformed into the ordinary differential equation by utilizing suitable similarity variables. The numerical outcomes of the reduced equations along with boundary conditions are solved by the Runge–Kutta–Fehlberg 45 (RKF-45) order method with shooting procedure. The numerical results are shown with the assistance of graphs. The impacts of various dimensionless constraints on velocity, thermal, and concentration profiles are studied under the occurrence and absence of nanoparticle aggregation. The study reveals that the primary velocity is enhanced with increasing values of the acceleration parameter, but secondary velocity diminishes. The impressions of the rotation parameter will improve the primary velocity. The concentration profiles will diminish with an improvement in the thermophoretic parameter. The surface drag force is greater in nanoparticles with aggregation than nanoparticles without aggregation in the Cfx case but a reverse behavior is seen in the Cfz case. Further, the rate of heat distribution increases with a rise in the solid volume fraction, whereas the rate of mass distribution grows as the thermophoretic parameter grows.

Inter-comparison of past and projected climatic trends in Puerto Rico: 1950–2100

Abstract Past and projected climatic trends in Puerto Rico in the period 1950–2100 are evaluated by detection of slope and fit in smoothed time series and by the mapping of local and regional trends using 5- to 50-km resolution products. New outcomes include second-order upward trends for evaporation and sea surface height. At a regional scale, Hadley Cell overturning is drying the mid-troposphere, inducing a northerly tendency for trade winds. The past rainfall trend (1950–2020) has increased ∼10% on the Atlantic-facing seaboard. Warming seas (+.02 °C/year) and rising vegetation fraction induce more evaporation that is deepening the moist boundary layer and sustaining thermal orographic precipitation over the island. Historical trends and model projections show a decrease in rainfall in spring and an increase in autumn, attributable to the retreat of the jet stream and the influence of transpiration, respectively. Outcomes reveal competition between small- and large-scale processes, and an island-wide water balance sustained by diurnal cycling. Adapting to the rising sea level makes pro-active coastal management a necessity. HIGHLIGHTS Past and future climate changes are similar. Dataset and model resolution of <50 km help to quantify climate change for small islands. New research suggests that second-order trends are replacing linear trends. Impacts due to sea level rise and coastal erosion require management.

Lake surface area expansion: Insights into the role of volcano-tectonic processes, Lake Beseka, East Africa

Study regionLake Beseka, Ethiopia Study focusLake Beseka has been expanding despite climatic and other relevant variables remaining largely the same over time. In this study, we applied an integrated approach based on multi-source datasets—Synthetic Aperture Radar (SAR), Landsat thermal band data, precipitation, and physicochemical and isotope water quality data—to understand the processes that govern the lake surface area expansion with a focus on the volcano-tectonic process. New hydrological insights for the regionOur findings show the following: (1) overall annual rainfall trend showed a declining trend, suggesting that rainfall is not the main source of water that led to the expansion of the lake; (2) recent vertical deformation rates reveal high subsidence rates on areas bordering the lake to the north, west, and southwest that are dissected by an echelon of fissures and faults, and physicochemical and isotopic water quality analysis from previous studies reveal dilution of the lake water by a new source of water in these parts; and (3) the thermal data analysis showed high land surface temperature values to the north of the lake, where a recent swarm of earthquakes were detected. We attributed the lake surface area growth to two processes: groundwater influx into the lake surface facilitated by active volcano-tectonic processes and volcano-tectonic-induced subsidence that creates favorable conditions for the water to expand to new areas.

Luminescent Citrate-Functionalized Terbium-Substituted Carbonated Apatite Nanomaterials: Structural Aspects, Sensitized Luminescence, Cytocompatibility, and Cell Uptake Imaging.

This work explores the preparation of luminescent and biomimetic Tb3+-doped citrate-functionalized carbonated apatite nanoparticles. These nanoparticles were synthesized employing a citrate-based thermal decomplexing precipitation method, testing a nominal Tb3+ doping concentration between 0.001 M to 0.020 M, and a maturation time from 4 h to 7 days. This approach allowed to prepare apatite nanoparticles as a single hydroxyapatite phase when the used Tb3+ concentrations were (i) ≤ 0.005 M at all maturation times or (ii) = 0.010 M with 4 h of maturation. At higher Tb3+ concentrations, amorphous TbPO4·nH2O formed at short maturation times, while materials consisting of a mixture of carbonated apatite prisms, TbPO4·H2O (rhabdophane) nanocrystals, and an amorphous phase formed at longer times. The Tb3+ content of the samples reached a maximum of 21.71 wt%. The relative luminescence intensity revealed an almost linear dependence with Tb3+ up to a maximum of 850 units. Neither pH, nor ionic strength, nor temperature significantly affected the luminescence properties. All precipitates were cytocompatible against A375, MCF7, and HeLa carcinogenic cells, and also against healthy fibroblast cells. Moreover, the luminescence properties of these nanoparticles allowed to visualize their intracellular cytoplasmic uptake at 12 h of treatment through flow cytometry and fluorescence confocal microscopy (green fluorescence) when incubated with A375 cells. This demonstrates for the first time the potential of these materials as nanophosphors for living cell imaging compatible with flow cytometry and fluorescence confocal microscopy without the need to introduce an additional fluorescence dye. Overall, our results demonstrated that Tb3+-doped citrate-functionalized apatite nanoparticles are excellent candidates for bioimaging applications.

Climate-inferred distribution estimates of mid-to-late Pliocene hominins

During the mid-to-late Pliocene (ca. 4–3 Ma), several hominin species were present in central Sahel, eastern and southern Africa. The potential for the discovery of hominin remains from this interval is limited by the availability of exposed Pliocene deposits and the ability to investigate them. As a result, most discoveries have been made in the Afar region of Ethiopia and in the Lake Turkana basin, thus unveiling only a portion of Pliocene hominins' probable geographical presence. In this study we provide a continental view of geographic areas potentially accessible to these hominins. To do so, we estimate the climatic envelope suitable for mid-to-late Pliocene hominin presence, using the earth system model IPSL-CM5A and the Maxent habitat suitability algorithm. Our analysis reveals high habitat suitability for these hominin species in semi-arid regions where annual thermal amplitude and mean annual precipitation are moderate, mostly corresponding to tropical xerophytic shrublands. Our habitat model estimates geographically continuous, suitable climatic conditions for hominins between central Sahel and northeastern Africa, but not between eastern and southern Africa. This discontinuity suggests that southern African and eastern African hominins were separated by an environmental barrier that could only be crossed during particularly favourable periods or by undertaking long-range dispersal over climatically hostile habitats. Under climate conditions of northern hemisphere summer at perihelion this climatic barrier is not present. In contrast, the Turkana basin, the Laetoli region, and a large part of southern Africa remain suitable for all precession angles, suggesting that these areas may have functioned as refugia. The constant presence of these stable areas combined with the periodic establishment of corridors for dispersion can potentially explain hominin diversity in eastern Africa. • Paleoclimatic reconstructions and HSM depict high suitability in semi-arid regions • Eastern and southern suitable areas are disconnected under mean Pliocene climate • Under specific precession configurations this climatic barrier disappears • Turkana basin and the Laetoli region could have work as climatic refugia • High Pliocene Hominin diversity could be linked with periodic presence of corridors.

CHARACTERIZATION OF THERMAL PRECIPITATOR IN SMOKE COLLECTOR BY USING PARTICLE COUNTER

Air pollution in major cities in many countries has reaching a very concerning level. One of thecause of air pollution is pollution caused by smoke aerosol. Smoke aerosols that has an averageparticle diameter of 0.1 μm – 1 μm can be found in cigarette smoke, diesel vehicle fume, industrialfume and many else. This condition will be worsen by the increase in the number of smokers, motorvehicles and industry. Therefore we need to pursue the control method for that kind of air pollution.In the literature study, it’s found that the cleaning method of air fi ltration for fi ne particle withdimension of 0.01 – 5 μm are by using thermal precipitator. Thermal precipitator is one method ofair fi ltration based on thermophoretic force, which is if there is a temperature difference betweentwo plates, it will cause the force that will push the particles between the two plates toward theplate that has lower temperature. In the effort to help control and reduce the air pollution, for thisstudy we made a thermal precipitator test equipment to deposit the particles in the air with the useof thermophoretic force. That force is the force applied to the particles that suspended in the fl uidfl ow. The temperature difference between two plates is set at ΔT=5, 10, 15, and 20oC. This studyutilized gas sensors to observe the characterization of thermal precipitator. From the experimentand analysis can be concluded that thermal precipitator can be applied as a smoke collector.

Synthesis of TiO2 nanoparticles out of fluoride solutions

In the paper, synthesis process of the TiO2 particles was discussed, from the fluoride solution, through TiO2·nH2O gel thermal precipitation and decomposition, and its impact on the further sintering of the obtained powders. It was demonstrated that the main phase of the obtained titania was anatase. Morphology of the obtained TiO2 can be controlled through variations of the precipitation temperature and the emulsifier concentration. It was found that the addition of the chloride ions during gel formation caused crystallization of the (NH4)2TiOF4 phase. When it underwent decomposition under heating, agglomerated particles in form of rods several micrometers long were synthesized. Obtained powders were sintered, and both the sintering process and the final bulk structures were examined. The results indicated the lowest microhardness of 540 kg/mm2 in the specimens prepared out of the powders synthesized without emulsifier, while the highest hardness of 1450 kg/mm2 was reached when the TiO2 particles had been precipitated at room temperature with emulsifier proportion С(Ti):C(OР9) = 1:0.5. However, further increase of the emulsifier concentration led to the decrease of hardness.

Temperature Responsive Polymer Conjugate Prepared by "Grafting from" Proteins toward the Adsorption and Removal of Uremic Toxin.

In this study, temperature-responsive polymer-protein conjugate was synthesized using a “grafting from” concept by introducing a chain transfer agent (CTA) into bovine serum albumin (BSA). The BSA-CTA was used as a starting point for poly(N-isopropylacrylamide) (PNIPAAm) through reversible addition-fragmentation chain transfer polymerization. The research investigations suggest that the thermally responsive behavior of PNIPAAm was controlled by the monomer ratio to CTA, as well as the amount of CTA introduced to BSA. The study further synthesized the human serum albumin (HSA)-PNIPAAm conjugate, taking the advantage that HSA can specifically adsorb indoxyl sulfate (IS) as a uremic toxin. The HSA-PNIPAAm conjugate could capture IS and decreased the concentration by about 40% by thermal precipitation. It was also revealed that the protein activity was not impaired by the conjugation with PNIPAAm. The proposed strategy is promising in not only removal of uremic toxins but also enrichment of biomarkers for early diagnostic applications.

Association mechanism of remimazolam-serum albumin nano-drug for potential clinical application

Bovine serum albumin (BSA) was selected to act as a stabilizer for the growth of remimazolam-BSA particles using thermal denaturation precipitation. The remimazolam-BSA NPs showed a sphere shape, with a ζ-potential of −11.3 mV and an average diameter of 84.3 nm under electron microscopy. The drug release study of remimazolam in vitro showed a sustained and controlled release pattern. The common ways of spectroscopy like circular dichroism (CD), UV–vis, and steady-state fluorescence were all used to investigate the physicochemical association properties. A moderate binding affinity between BSA and remimazolam with a stoichiometry of 1:1 was revealed by fluorescence results (binding constant: 1.87 × 104 M−1 at body temperature). The participation of hydrophobic forces in the formation of the complex has been confirmed by analyzing the thermodynamic results of the binding data (ΔS○ = 110 J mol-1 K-1 and ΔH○ = 8.63 × 103 J mol-1). The prior remimazolam binding site is located in site II of BSA with slight protein conformational changes and probable energy transfer.