Atomic Force Microscopy Results Research Articles

On the Effect of Randomly Oriented Grain Growth on the Structure of Aluminum Thin Films Deposited via Magnetron Sputtering

The microstructure of aluminum thin films, including the grain morphology and surface roughness, are key parameters for improving the thermal or electrical properties and optical reflectance of films. The first step in optimizing these parameters is a thorough understanding of the grain growth mechanisms and film structure. To investigate these issues, thin aluminum films with thicknesses ranging from 25 to 280 nm were coated on SiOx/Si substrates at ambient temperature under high-vacuum conditions and a low argon pressure of 3 × 10−3 mbar (0.3 Pa) using the radio frequency magnetron sputtering method. Quantitative analyses of the surface roughness and nanograin characteristics were conducted using atomic force microscopy (AFM), transmission electron microscopy (TEM), and X-ray diffraction. Changes in specular reflectance were measured using ultraviolet–visible and near-infrared spectroscopy. The low roughness values obtained from the AFM images resulted in high film reflectivity, even for thicker films. TEM and AFM results indicate monomodal, randomly oriented grain growth without a distinct columnar or spherical morphology. Using TEM cross-sectional images and the dependence of the grain size on the film thickness, we propose a grain growth mechanism based on the diffusion mobility of aluminum atoms through grain boundaries.

PVDF‐based nanocomposite coatings with superhydrophobic and antibacterial properties on stainless steel surfaces

AbstractIn this study, using a spray‐coating technique, stainless steel surfaces were coated with polyvinylidene fluoride (PVDF) and carbon soot nanoparticles. We imparted various surface properties onto the coatings' surfaces by varying the nanoparticle content and the preparation method. The main aim was to develop antibacterial surfaces by inducing superhydrophobic properties in stainless steel surfaces. In a one‐step preparation method, 5% and 10% of nanoparticles were insufficient to achieve superhydrophobicity, whereas 20% significantly increased the water contact angle to 153°. Morphological evaluations revealed the formation of a nano‐scale structure, which also led to a staggering antibacterial rate of 99.5% against Listeria monocytogenes. Using a two‐step preparation, soot nanoparticles were localized at the coating's top layer, which led to superhydrophobicity at a lower nanoparticle content (10%). However, the bacterial adhesion study showed a lower antibacterial rate (~93%). The difference in bacterial adhesion results was explained by various roughness structures according to the atomic force microscopy results. The developed system has a promising potential to be used as self‐cleaning and antibacterial coatings in the medical and food industries.Highlights Stainless steel surfaces were coated with PVDF and carbon soot nanoparticles Imparted various surface properties onto the coatings' surfaces Developed antibacterial surfaces by inducing superhydrophobic properties Using a two‐step, soot nanoparticles were localized at the coating's top layer Bacterial adhesion study showed a lower antibacterial rate (~93%).

Leaching Peculiarity of Uranium-Containing Layered Double Hydroxide Sediment Varied with Environmental Anions.

In this research, we focus our attention on the leaching peculiarity of uranium-containing Mg-Al layered double hydroxide (LDH) which is one kind of waste sediment in uranium tailings, generated by the alkalinization of uranyl raffinate. The effect of inorganic (CO32-, SO42-, PO43-) and organic (C2O42-, C6H6O72-, C6H16O24P62-) anions were investigated. Atomic force microscopy result showed that the thickness of CO32--LDH increased to 8.6 nm compared to original LDH whose thickness was 6.7 nm. Compared with the control sample (5.58 μm), the grain size with C6H16O24P62- anion grew to 7.04 μm. A large amount of CO32- can stay in LDH, up to 1.78 mol percent, while the C6H16O24P62- anion was only 0.41 mol percent. X-ray diffraction results showed that the anions could change the crystal structure of LDH, especially the C6H18O24P6 anion, and theoretical calculation also conformed this result. The leaching tests showed that the introduction of anions improved the leaching efficiency of UO22+ from LDH. The introduction of anions destroyed the super buffer property of LDH. Theoretical calculation results indicated that the anions could grab UO22+ and help the UO22+ escape from the LDH. This research gave guidance for long-term disposal of uranium-containing tailings.

Rheological and adhesive improvements of terminal blend rubberized asphalt via fumed silica nanoparticle modification

Due to the high degree of desulfurization and depolymerization of crumb rubber (CR) particles in terminal blend rubberized asphalt (TBRA), their elasticity and adhesive performance are insufficient. To address this, the study utilized low-cost fume silica nanoparticles (FSNPs) to enhance the elasticity and adhesive properties. TBRA binders with varying CR contents (30 %, 40 %, 50 %) were modified using different dosages of FSNPs (2 %, 4 %, 6 %). The microstructure of FSNPs was examined through TEM and SEM. Using a dynamic shear rheometer (DSR) test, contact angle test, and atomic force microscope (AFM) test, the effects of FSNPs on the rheological properties, surface energy, and adhesive properties of TBRA binders were evaluated. The results showed significant improvements in the deformation resistance and elasticity of the TBRA binders modified with FSNPs. This is attributed to the branched network structure of FSNPs, which notably enhances the binder's cohesion, thereby strengthening its resistance to shear deformation and improving elasticity. FSNPs effectively reduce the moisture sensitivity of TBRA, due to the hydrophilic hydroxyl groups on FSNPs being replaced by hydrophobic methyl groups (-CH3). The inadequate bonding performance of TBRA can be attributed to the high levels of extensively depolymerized and desulfurized CR particles, which reduce the cohesiveness of the binder. The addition of FSNPs, although it lowers the surface energy of TBRA binders, significantly enhances their cohesiveness due to the branched network structure, thereby improving their bond performance. AFM results indicate that FSNPs enhance the adhesive strength of the TBRA binder surface due to their high specific surface area, which provides more van der Waals forces and electrostatic interactions. For economic efficiency, an addition of 4 % is recommended for TB30, and 2 % for TB40 and TB50. At these specified concentrations, the bond strength of the TBRA binder can be increased by 45–55 %.

Probing the interactions between asphaltenes and a PEO-PPO demulsifier at oil–water interface: Effect of temperature

HypothesisAsphaltenes are primary stabilizers in water-in-oil (W/O) emulsions that cause corrosion and fouling issues. In oil sands industry, oil/water separation processes are generally conducted at high temperatures. A high temperature is expected to impact the interactions between asphaltenes and emulsion breakers (EBs), consequently influencing demulsification performance. ExperimentsThe adsorption and interactions of asphaltenes and a PEO-PPO type EB (Pluronic F68) at the oil–water interface were investigated at various temperatures, using tensiometer, quartz crystal microbalance with energy dissipation (QCM-D), and atomic force microscopy (AFM). The effect of temperature on EB’s demulsification performance was explored through bottle tests. Additionally, demulsification mechanisms were studied using direct force measurements with the droplet probe AFM technique. FindingsDynamic interfacial tension and QCM-D results demonstrate that the PEO-PPO type EB exhibits higher interfacial activity than asphaltenes and can disrupt rigid asphaltene films at the oil–water interfaces. Elevated temperatures accelerate the displacement of adsorbed asphaltenes by EB molecules, leading to sparse interfacial films, rapid droplet coalescence, and improved demulsification efficiency (supported by AFM and bottle test results). This work provides valuable insights into interfacial interactions between asphaltenes and EB at different temperatures, enhancing the understanding of demulsification mechanisms and offering useful implications for the development of efficient EBs to enhance oil/water separation performance.

Leaching process assisted by cetyltrimethylammonium chloride for weathered crust elution-deposited rare earth ores: Leaching behavior, kinetic analysis and interfacial regulation

Magnesium salts are commonly employed as ammonium-free leaching agents in the extraction of weathered crust elution-deposited rare earth ores (WCE-REO). Nonetheless, these salts frequently face technical challenges, including relatively low leaching rates and inadequate permeability in the in-situ leaching process. In this study, cetyltrimethylammonium chloride (CTAC) was used as a novel leaching aid agent to improve the rare earth leaching process. The effects of CTAC and pH on the rare earth leaching behavior and permeability was investigated. The leaching kinetic model was established and the regulation mechanism by which CTAC interacts with clay mineral surfaces was revealed for rare earth leaching process enhanced by CTAC. The results indicate that the appropriate amount of CTAC can increase the permeation velocity by 1.16×10−4 cm·s−1. Moreover, the rare earth leaching rate increased from 83.75 % to 95.65 %, accompanied by a reduction in leaching equilibrium time under optimal conditions. However, a higher concentration of CTAC results in a lower permeation velocity due to the increasing viscosity and the hydrophilicity. The relatively low pH will affect permeability of composite leaching agent in the ore pillar, diminishing its beneficial impact on rare earth leaching. The kinetic equation, fitted by the shrinking core model, suggests that the leaching adheres to an internal diffusion control mechanism, underscoring mass transfer as the pivotal limiting factor in rare earth leaching. CTAC reduces surface tension and viscosity, facilitating the permeation of the leaching solution into the rare earth ore. Furthermore, CTAC can be adsorbed on the surface of rare earth mineral particles, increasing the contact angle of clay minerals, elevating the Zeta potential, and diminishing the thickness of the diffusion layer, thus promoting mass transfer during leaching. The results of atomic force microscopy (AFM) analysis shows that the appropriate amount of CTAC adsorbed on rare earth ores can decreases the thickness of the hydration film on the particles’ surface, further improving the mass transfer efficiency during the leaching process. The findings of this study offer new insights into the green and efficient extraction of rare earth resources from both theoretical and technical perspectives.

Molecular interaction of a protease inhibitor, leupeptin, with human serum albumin: Insights from calorimetry, spectroscopy, microscopy, and computational approaches

Leupeptin (LPN) possesses anti-inflammatory and inhibitory effects on periodontitis and gingivitis, and it also inhibits human coronavirus and SARS-CoV-2 in cells. The characterisation of its interaction with human serum albumin (HSA), the key transport protein in the blood circulation of the human body, contributes essential information to the drug's pharmacokinetic properties. Various techniques, such as isothermal titration calorimetry (ITC), circular dichroism (CD) spectroscopy, atomic force microscopy (AFM), molecular docking, and molecular dynamics simulation (MDS), were employed to characterise the LPN-HSA interaction. The ITC result revealed a moderate binding affinity in the LPN-HSA interaction with a binding constant (Ka) value of 4.27 ± 0.27 × 106 M−1. The thermodynamic analysis indicated that LPN binding to HSA was spontaneous, resulting from a negative Gibbs free energy change (∆G° = − 37.91 ± 0.04 kJ mol−1) and involving an exothermic reaction due to a combination of a negative enthalpy change (∆H° = − 11.4 ± 0.9 kJ mol−1) and a positive entropy change (∆S° = 88.82 ± 3.4 J mol−1K−1). The HSA secondary structure remained unaltered upon the addition of LPN, as evident from the far-UV CD results. AFM results showed HSA morphological changes induced by LPN binding due to the occurrence of aggregates in the LPN-HSA complex. Molecular docking results predicted that LPN preferably binds to site III of HSA, involving hydrogen bonds, electrostatic, van der Waals forces, and hydrophobic forces. The MDS demonstrated a slight deviation and fluctuation, which supported the overall stability of the LPN-HSA system. Thus, these findings provide additional information on the pharmacokinetics of this drug and contribute to designing new drugs for clinical use, particularly those related to inflammatory diseases.

Investigation of microstructure, corrosion and mechanical properties of iron and holmium modified Sn-3.0Ag0.5Cu solder alloy with ultrasonic treatment

This research investigated the microstructure, corrosion behavior and mechanical properties of iron and holmium modified Sn-3.0Ag-0.5Cu solder alloy with ultrasonic treatment. The results demonstrated that the distribution of the phases in the ultrasonically treated solder alloys became homogeneous and the microstructure of ultrasonically treated solder alloys were more refined. The average grain size of ultrasonically treated solder alloys was reduced from 206.7 μm to 184.1 μm. A significant increase in the tensile strength from 38.75 MPa to 47.38 MPa was found in the ultrasonically treated solder alloys. The polarization curves results indicated that the solder alloys treated with ultrasound possessed lower corrosion current density and the results of atomic force microscopy suggested that roughness of corrosion products morphology was reduced. Furthermore, the electrochemical impedance spectroscopy (EIS) results indicated that the ultrasonically treated solder alloys had larger diameter of the semicircular loops and higher total impedance values.

Exploring asphaltene aggregation: Model systems based on toluene-heptane mixtures

This work evaluates how chemical characteristics, such as polarity and aromaticity, can affect asphaltene aggregation. The asphaltene fraction was extracted from two different crude oils by precipitation in n-heptane, and these extracted asphaltenes were named A and B. Based on infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR) analyses, we found that asphaltenes B present greater aromaticity. According to X-ray photoelectron spectroscopy (XPS), asphaltene B showed higher heteroatom content. Model systems based on toluene/n-heptane/asphaltene (0.05 g/L) were prepared to evaluate the aggregation/precipitation of asphaltenes. Dynamic light scattering (DLS) analysis of aggregation kinetics revealed that aromatic asphaltenes with higher heteroatom content tend to form larger aggregates. Moreover, hydroxyl content exhibits a greater impact on aggregation compared to diffusivity. Furthermore, once the aggregates reach a critical size, the suspension stability is reduced, and the aggregates sediment. The atomic force microscopy (AFM) and DLS results revealed a wide range of particle size distribution. The larger clusters likely consisted of smaller aggregates that adhered together. Still, we highlight that the sizes of these aggregates determined by AFM are not directly comparable to the measurements obtained from DLS. The drying of the samples for the AFM measurements probably affects the asphaltene aggregation process. For this reason, the results obtained from the AFM and DLS techniques are not comparable.

Effects of Nanofillers and Synergistic Action of Carbon Black/Nanoclay Hybrid Fillers in Chlorobutyl Rubber

Nanocomposites based on chlorobutyl rubber (CIIR) have been made using a variety of nanofillers such as carbon black (CB), nanoclay (NC), graphene oxide (GO), and carbon black/nanoclay hybrid filler systems. The hybrid combinations of CB/nanoclay are being employed in the research to examine the additive impacts on the final characteristics of nanocomposites. Atomic force microscopy (AFM), together with resistivity values and mechanical property measurements, have been used to characterise the structural composition of CIIR-based nanocomposites. AFM results indicate that the addition of nanoclay into CIIR increased the surface roughness of the material, which made the material more adhesive. The study found a significant decrease in resistivity in CIIR–nanoclay-based composites and hybrid compositions with nanoclay and CB. The higher resistivity in CB composites, compared to CB/nanoclay, suggests that nanoclay enhances the conductive network of carbon black. However, GO-incorporated composites failed to create conductive networks, which this may have been due to the agglomeration. The study also found that the modulus values at 100%, 200%, and 300% elongation are the highest for clay and CB/clay systems. The findings show that nanocomposites, particularly clay and clay/CB hybrid nanocomposites, may produce polymer nanocomposites with high electrical conductivity. Mechanical properties correlated well with the reinforcement provided by nanoclay. Hybrid nanocomposites with clay/CB had increased mechanical properties because of their enhanced compatibility and higher filler–rubber interaction. Nano-dispersed clay helps prevent fracture growth and enhances mechanical properties even more so than CB.

Understanding the Impact of Chain Mobility on Conformational Evolution and Kinetics of Mesophase Formation in Poly(ʟ-lactide) under Low-Pressure CO2.

Although the mesomorphic phase as an intermediate state has been introduced to understand polymer crystallization, the understanding of the mesomorphic phase is far from complete. Here, the effect of chain mobility on the mesophase structuring in melt-quenched poly(ʟ-lactide) (PLLA) treated in low-pressure CO2 at 1.6-2.0 MPa and 0 °C was investigated using infrared (IR) spectroscopy, differential scanning calorimetry (DSC), and atomic force microscopy (AFM). The IR and AFM results demonstrated that the final degree of order and the kinetics of structural evolution during the CO2-induced mesophase formation were critically dependent on the CO2 pressure. This was attributed to the distinct dynamics of conformational evolution (gg to gt conformer transition) due to the different CO2 pressures. The thermal behavior from the DSC results showed that CO2 pressure dominated both the scale and dynamics of the chain motion of PLLA. At a lower CO2 pressure of 1.6 MPa, smaller-scale segmental motion was not replaced by the larger-scale cooperative motion that occurred at a relatively higher CO2 pressure of 2 MPa, which was favorable for faster mesophase formation. Consequently, by inhibiting direct crystallization under limited mobility conditions, it was demonstrated that different chain mobility controlled by CO2 pressure and thus CO2 solubility impacted the dynamics of the mesophase formation of PLLA. The present results have implications for understanding the role of chain mobility in determining the intermediate structural phases in semicrystalline polymers.

Deposition time dependent structural and optical properties of polycrystalline [formula omitted] films

Sputtering-derived InGaZnO4 (IGZO) thin films were grown on quartz substrates and undergone post-deposition annealing at 700 °C for 2hr in N2 ambient. The influence of deposition time or film thickness on the morphological, structural and optical properties of polycrystalline IGZO thin films has been systematically investigated by means of characterization from field-emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), high resolution X-ray diffraction (HRXRD) and ultraviolet–visible–near infrared (UV–Vis–NIR) spectrophotometer. Results of AFM have shown that the root-mean-square (RMS) surface roughness of the IGZO films increases from 0.888 to 2.640 nm as the deposition time is extended from 50 to 250min. Analysis of XRD indicates that all the films are in polycrystalline phase, with crystallites growing into larger size accordingly to increasing deposition time. Appealingly and scarcely ever reported, the XRD diffraction planes can be separated into three domains, such as (0 0 l), (1 0 l) and (1 1 l) with different growth thicknesses. Optical measurement suggests that the optical bandgap have redshifted from 3.55 to 3.31eV at longer deposition time. Related mechanics about the change in physical properties against deposition time have been elaborated in detail. The validity of Swanepoel method, 1983 in deriving the refractive index of thick IGZO films has also been discussed.

A study of pomegranate peel extract effect on corrosion inhibition performance on aluminum in HNO3 solution

Green corrosion inhibitors have an important role in reducing the corrosion rate of metals and the effects of toxic chemicals in the environment. In this study, the inhibition effect of pomegranate peel extract (PPE) with concentration of 0.5, 1, 1.5, 2, 2.5 and 3 g/L on the aluminum 1050 alloy corrosion behavior in the nitric acid solution investigates using the weight loss, electrochemical techniques, scanning electron microscope (SEM), atomic force microscope (AFM), contact angle images, gas chromatography-mass spectrometer (GC-MS) analysis, fourier transform Infrared spectroscopy (FTIR) and ultraviolet radiation (UV-IR). And, the (UV-IR), (GC-MS), and FTIR results confirm the presence of many organic compounds (Containing the N, S, and O atoms), which are responsible for inhibitor performance and absorption phenomena. Meanwhile, the electrochemical impedance results (EIS) indicate that the double layer capacity decreases and the corrosion resistance (Corrosion current density (icorr) from 0.128 to 0.009 mA/cm2) increases with the increase of the inhibitor concentration (The inhibition efficiency increased with increasing the inhibitor concentration from % 54.29 to the % 92.58 at (1–3 g/L). In addition, the corrosion current density decreases with the increase of the inhibitor concentration using the potentiodynamic polarization (PDP) test. However, the corrosion rate enhances with increasing the temperature. From the other hand, quantum chemical (QC) calculation and molecular dynamics (MD) simulation perform to investigate the theory of the adsorption mechanism. According to these studies, the adsorption of PPE on the aluminum 1050 alloy surface is agreement with the langmuir isotherm and as a result it is a mixed-type inhibitor. In final the SEM and AFM results show that the corrosion rate of the aluminum 1050 alloy surface is significantly reduced after the addition of the inhibitor to the corrosive environment. Furthermore, the contact angle image shows that the inhibited aluminum surface has a hydrophobic property in an aqueous solution. And, the QC calculation and MD simulation clarify well the thin layer formation due to the good adsorption of inhibitor (PPE) on the surface of aluminum 1050 alloy in the nitric acid solution, theoretically. It is concluded that PPE will inhibit the surface of aluminum against the corrosion agents in acidic environment and can use as a green inhibitor.

Deposition of nickel-titanium coating on stainless steel 316L by direct current sputtering for bio-implants: Electrochemical, microstructural, and morphological investigations

In general, the application of coatings provides vital protection for medical devices with a host of beneficial properties such as biostability and biocompatibility, chemical barrier, and micro-encapsulation. In the current work, a nickel-titanium (NiTi) system was deposited on stainless steel (SS316L) by the direct current sputtering (DCS) technique to estimate the corrosion behavior in the simulated body fluid (SBF) at 37 °C. The characterization of the coating layer was done using X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive x-ray spectroscopy (EDX) techniques to know the phases, elemental composition, and structure of the coating that indicated the formation of the Ni3Ti phase as a flake-shaped structure with 2.6 and 0.4 wt% of Ni and Ti, respectively. The results of atomic force microscopy (AFM) showed a decrease in surface roughness from 25.2 to 11.05 nm after coating due to a decrease in the mean diameter of particles from 710.8 to 579.9 nm after coating. The data corrosion test showed the change of corrosion potential to a more noble value with minimizing the corrosion current density as well as the improvement of resistance after coating from 6.91 × 103 to 25.49 × 103 Ω.cm2 to get protection efficiency equal to 73.9 %. In a cyclic polarization test, it can be seen that the passivity region shifts to lower current density values. Microhardness was also measured to show an increase from 187 to 366 HV due to the selected technique of coating that gives more hardness; the measured wettability did not change the contact angle of the uncoated specimen to keep it at 90°; and finally, the histological analysis did not show any severe infection or inflammation. All these observations can suggest the NiTi coating for bio-applications.

Low-Temperature Migration-Enhanced Epitaxial Growth of High-Quality (InAs)4(GaAs)3/Be-Doped InAlAs Quantum Wells for THz Applications

This investigation explores the structural and electronic properties of low-temperature-grown (InAs)4(GaAs)3/Be-doped InAlAs and InGaAs/Be-doped InAlAs multiple quantum wells (MQWs), utilizing migration-enhanced epitaxy (MEE) and conventional molecular beam epitaxy (MBE) growth mode. Through comprehensive characterization methods including transmission electron microscopy (TEM), Raman spectroscopy, atomic force microscopy (AFM), pump–probe transient reflectivity, and Hall effect measurements, the study reveals significant distinctions between the two types of MQWs. The (InAs)4(GaAs)3/Be-doped InAlAs MQWs grown via the MEE mode exhibit enhanced periodicity and interface quality over the InGaAs/Be-InAlAs MQWs grown through the conventional molecule beam epitaxy (MBE) mode, as evidenced by TEM. The AFM results indicate lower surface roughness for the (InAs)4(GaAs)3/Be-doped InAlAs MQWs by using the MEE mode. Raman spectroscopy reveals weaker disorder-activated modes in the (InAs)4(GaAs)3/Be-doped InAlAs MQWs by using the MEE mode. This originates from utilizing the (InAs)4(GaAs)3 short period superlattices rather than InGaAs, which suppresses the arbitrary distribution of Ga and In atoms during the InGaAs growth. Furthermore, pump–probe transient reflectivity measurements show shorter carrier lifetimes in the (InAs)4(GaAs)3/Be-doped InAlAs MQWs, attributed to a higher density of antisite defects. It is noteworthy that room temperature Hall measurements imply that the mobility of (InAs)4(GaAs)3/Be-doped InAlAs MQWs grown at a low temperature of 250 °C via the MEE mode is superior to that of InGaAs/Be-doped InAlAs MQWs grown in the conventional MBE growth mode, reaching 2230 cm2/V.s. The reason for the higher mobility of (InAs)4(GaAs)3/Be-doped InAlAs MQWs is that this short-period superlattice structure can effectively suppress alloy scattering caused by the arbitrary distribution of In and Ga atoms during the growth process of the InGaAs ternary alloy. These results exhibit the promise of the MEE growth approach for growing high-performance MQWs for advanced optoelectronic applications, notably for high-speed optoelectronic devices like THz photoconductive antennas.

Microorganisms and bacterial cellulose stability of Kombucha under different manufacture and storage conditions.

It is crucial to clarify the stability of Kombucha in the manufacture and storage stages due to the extensive study on the fermented products of Kombucha and the increase in the use of bacterial cellulose (BC). This study aimed to evaluate the stability of Kombucha in different manufacturing and storage temperatures within a certain time period. The stability of microorganisms and BC in Kombucha was investigated through regular replacement with the tea media at 28 and 25°C for manufacture, and the storage temperature of Kombucha was at 25, 4, and -20°C. Morphological observations of the BC in Kombucha ended at 28 and 25°C for manufacture and storage were performed using atomic force microscopy (AFM) before inoculation. The viable cell counts and AFM results showed that the stability of Kombucha during manufacture was better at 28°C than at 25°C, with higher microbial viability and BC productivity in the former at the time of manufacture, whereas 25°C was more favorable for the stability of Kombucha during storage. At the same temperature of 25°C, the manufacturing practice improved the microbial viability and BC stability compared with storage; the pH value of Kombucha was lower, and the dry weight of BC was higher during storage compared with manufacture. The maximum BC water holding capacity (97.16%) was maintained by storage at 4°C on day 63, and the maximum BC swelling rate (56.92%) was observed after storage at -20°C on day 7. The research was conducted to provide reference information for applying Kombucha and its BC in food and development in other industries.

Nanocomposite-Supported Polymeric Composites Prepared with Different Deposition Bases: Characterization and Application in X-ray Shielding

This study deals with the preparation of magnetite nanoparticles (NPs) via a coprecipitation method using several precipitation bases: binary precipitator (NH4OH), mono precipitator (NaOH), and weak precipitator (Ca(OH)2). The prepared magnetite NPs were identified using X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) analysis, surface area analysis, magnetic properties, Fourier-transformed infrared spectra (FT-IR), and ultra-violet UV–visible spectra. As a result, the phases of the produced magnetite NPs were unaffected by the use of various bases, but their crystallite sizes were affected. It was found that the binary base provided the smallest crystallite size, the mono base provided an average size, and the weak base provided the largest crystallite size. The UV–visible absorption spectroscopy investigation revealed that the absorption and the energy gap rose with a reduction in nanoparticle size. The prepared magnetite NPs were used to manufacture polymeric-based nanocomposites employed as protective shields from low-energy X-rays that are light in weight. These samples were identified using XRD, atomic force microscopy (AFM), and FT-IR spectroscopy. The crystallite size was slightly larger than it was in the case of magnetite NPs. This is consistent with the results of AFM. The interference between the two phases was observed in the results of the FT-IR spectra. The effects of the size of the magnetite NPs on the attenuation tests, linear attenuation coefficient, mass attenuation coefficient, half-value layer, and mean free path were investigated. The results showed that the efficiency of using manufactured shields increases with the decrease in the NPs size of the magnetite used as a reinforcement phase for a range of low operating voltages.

Influence of core-shell polydopamine-barium titanate doping on the osseointegration and cytotoxicity of the polypyrrole coatings applied by ECD on Nitinol orthopedic implants

In the current study, a thin polydopamine (PDA) layer of around 5 nm was created on the barium titanate (BT) nanoparticles through self-polymerization of dopamine. The produced modified PDA/BT core-shell nanoparticles, termed PBT, were co-electrodeposited with polypyrrole (PPy) onto Nitinol (NiTi) alloy substrates in concentrations ranging from 1 to 10% by weight to produce PPy/PBT composite coatings. The incorporation of these particles changed PPy's cauliflower morphology into a rougher but more compact nodular morphology. According to the atomic force microscopy results, the average surface roughness of PPy coating increased from 44.2 nm up to 80.2 nm by the co-deposition of PBT. Aside from variations in morphology and roughness values, all of the PPy and PPy/PBT coatings demonstrated hydrophilicity. Nonetheless, while the majority of the composite coatings had higher water contact angle (WCA) than the unreinforced PPy, the PPy/10PBT composite coating had the lowest WCA of all samples, measuring 56.9°. The piezoelectric responses of the coatings were also examined, and the best specimen was the PPy/5PBT composite coating with an enhanced output voltage of approximately 400 mV. Finally, MC3T3 mouse osteoblast cells were used for in vitro cell culture evaluations. While healthy cells were evenly distributed on the surface of all coatings after 3 days, indicating biocompatibility, cell density on composite coatings was higher than on unreinforced PPy coating. According to the MTT experiment, the vitality of MC3T3 osteoblast cells on the surface of PPy/5PBT composite coating was more than 30% greater than that on the surface of PPy coating.

Unveiling the molecular interaction of hepatitis B virus inhibitor, entecavir with human serum albumin through computational, microscopic and spectroscopic approaches

Molecular docking, molecular dynamics (MD) simulation, atomic force microscopy (AFM) and multi-spectroscopic techniques were selected to unveil the molecular association between the hepatitis B virus (HBV) inhibitor, entecavir (ETR), and the major blood plasma transporter, human serum albumin (HSA). The entire docking and simulation analyses recognized ETR binding to subdomain IIA (Site I) of HSA through hydrogen bonds, hydrophobic and van der Waals forces while maintaining the complex’s stability throughout the 100 ns. A gradual lessening in the Stern-Volmer quenching constant ( K sv ) with rising temperatures registered ETR-induced quenching of HBV fluorescence as static quenching, thus advising complexation between ETR and HSA. The further advocation of this conclusion was seen from a larger value of the biomolecular quenching rate constant (( kq ) > 1010 M−1s−1), changes in the spectra (UV-Vis absorption) of HSA following ETR inclusion and ETR-induced swelling of HSA in the AFM results. The ETR appeared to bind to HSA with moderate affinity ( K a = 1.87 − 1.19 × 10 4 M−1) at 290, 300 and 310 K. Significant alterations in the protein’s secondary and tertiary structures, including changes in the protein’s Tyr/Trp microenvironment, were also detected by circular dichroism and three-dimensional fluorescence spectra when the protein was bound to ETR. The findings of the drug displacement study backed the docking results of Site I as ETR's preferred binding site in HSA. Communicated by Ramaswamy H. Sarma

Self-assembly embedding of curcumin by alkylated rice bran protein

Lysine-rich rice bran protein (RBP) can be used as raw material for alkylation modification to improve the self-assembly performance of protein. The results of 1H NMR, degree of alkylation, and DSC analysis showed that the alkyl chain was successfully attached to the RBP. The surface hydrophobicity and absolute ζ-potential increased. The three-dimensional structure of the alkylated RBP (ARBP) become more porous and ARBP-2 was selected as the material for embedding curcumin. The XRD results revealed that curcumin induced self-aggregation of ARBP-2 and the inclusion of curcumin was attained. The maximum encapsulation efficiency of curcumin was 82.67 % and the maximum loading amount was 171.37 g/100 g RBP. The results of atomic force microscopy (AFM), particle size, and polydispersity index (PDI) analyses revealed that the particles in the system were aggregated after curcumin was added. Curcumin was well protected by encapsulation in the self-assembled particles. Thus, this study provides a new strategy for the embedding and delivery of curcumin.