Bulletin of Materials Science最新文献

A structural study of the transformation of 6√3 reconstruction on the surface of a 4H–SiC substrate into quasi-free epitaxial graphene was carried out by the reflection high-energy electron diffraction (RHEED) method. The conversion was carried out via hydrogen intercalation between the reconstructed layer and the adjacent top layer of SiC. The initial 6√3 reconstruction was obtained during short sublimation annealing of the 4H–SiC substrate in an argon medium. A slight violation of the 6√3 reconstruction layer formation uniformity was found. The results of the study of the crystal structure of quasi-free-standing graphene and single-layer graphene comprising a buffer layer formed on 4H–SiC in the traditional way in an Ar atmosphere without intercalation were compared.

Cotton gauze (CG) is the most commonly used primary wound dressing to protect wounds from the external environment. However, it is highly susceptible to fouling due to the adhesion of bacteria present on the wound surface. Bacterial colonization of the dressing is detrimental as it aids in wound infection and delays wound healing. To mitigate this issue, the objective of this study was to transform the inert CG into a fouling-resistant wound dressing that can actively resist bacterial adhesion and also prevent biofilm formation on the surface of cotton. In this work, a facile method of modifying commercial CG using oxidized dextran (Odex) was developed. Odex was derived from dextran via periodate oxidation reaction and then coated over the CG using mussel-inspired chemistry. The resultant Odex-modified CG demonstrated a substantial reduction in bacterial adhesion after 4 h of incubation in bacterial suspension. The modified gauze suppressed biofilm formation, achieving ~83% reduction in viable bacterial count as compared to unmodified CG after 48 h of incubation in the bacterial suspension. In addition, the modified CG also showed good breathability, wettability and moisture retention properties. The results suggest a promising approach of transforming inert CG into a potential fouling-resistant wound dressing for the management of wound infections.

The enhancement of light absorption and surface area in monocrystalline solar cells is achieved through anisotropic etching, with the aim of improving its conversion efficiency. Nevertheless, the conventional method of anisotropic etching is constrained in its capacity for incrementing surface area. Herein, a promising texturization process in the form of a homogenous and uniform pyramidal structure is proposed with two-step texturing processes: cyclic voltammetry (CV) treatment and the alkali anisotropic etching method on the silicon wafer surface. Prior to and following the alkali texturing process, the silicon surface was modified using the CV treatment. The effect of this approach was investigated under different CV cycles (20, 40, 60 and 80 cycles) in a 0.5 M Na₂SO₄ aqueous electrolyte with pH ~ 7. Based on the field emission scanning electron microscope (FESEM) micrographs and UV-visible spectrometer (UV-Vis) measurements, the wafer textured with 60 cycles of CV treatment and an alkali anisotropic etching process tremendously improves the surface morphology and decreases the front surface reflection. As a result, the size and height of the pyramid formed were 2.1–2.3 µm and 0.6–1.9 µm, respectively. Moreover, the outlined methodology facilitates a substantial decrease in surface damage and is applicable in the Si texturization process for the manufacturing of solar cells.

(1−x)BiFeO₃–(x)Pb(Fe_2/3W_1/3)O₃ ceramics (x = 0.00–0.30) were synthesized by a solid-state reaction route. Structural characterization was done by X-ray diffraction and Raman spectroscopic studies. Existence of rhombohedral symmetry with the (R3c) space group up to x ≤ 0.20 and a transition to cubic symmetry with the (Pmoverline{3 }m) space group for x > 0.25, confirmed with Rietveld refinement. Raman studies also confirm the significant modification at the A-site due to the replacement of Bi³⁺ atom by Pb²⁺ indicating the structural modification in Pb(Fe_2/3W_1/3)O₃ (PFW) in BiFeO₃ (BFO). Morphology and microstructure were observed using SEM micrographs and the average grain size was decreased with the increase in PFW concentration (x). Enhanced magnetic and ferroelectric properties were observed up to x ≤ 0.20, which can be attributed to the suppression of spin-canted structure and reduced leakage currents. Hence, BFO–PFW solid ceramics, with a limited low composition region, can be useful for magneto-electric device applications.

Nowadays, an economically cheaper, NIR fluorescent probe is needed in order to identify the cancerous cells without skin cells damage. For this purpose, conventional conducting polymers are used. Under N₂ environment, the chemical polymerization of o-chloroaniline (OCA) was initiated by peroxydisulphate (PDS) with the help of rosebengal (RB) dye, both in the presence and absence of a 3% weight loading of Ag⁺ ion. The weight of the polymer was used to calculate the rate of polymerization (R_p) and yield percentage. Additionally, FTIR, UV–visible, fluorescence emission, thermogravimetric analysis, scanning electron microscopy and differential scanning calorimetry were used to analyse the poly(o-chloroaniline) (POCA) structure–property relationship. The FTIR spectrum confirmed the presence of benzenoid and quinonoid structures in POCA chains. The percentage yield and R_p both marginally increased in the presence of Ag⁺ ions. The T_g of RB end-capped POCA/Ag nanocomposite system was determined as 103°C. The energy of activation (E_a) value of 66.17 kJ mol⁻¹ was found for the structural degradation of RB in RB end-capped POCA. In comparison to the straightforward RB end-capped POCA system, the POCA/Ag^o nanocomposite system has higher thermodynamic parameter values. The experimental findings are thoroughly examined and contrasted with the values given in the literature.

We developed a facile synthetic method to construct a novel sandwiched coaxial core–shell heterojunction electrode by combining MnO₂ nanoflakes wrapped in Au nanoparticles decorated NiCo₂O₄ nanowires (NW) with carbon fiber cloth (NiCo₂O₄@Au@MnO₂). XRD, SEM and TEM techniques were used to characterize the structures of NiCo₂O₄@Au@MnO₂. Electrochemical measurements confirmed that such nanostructured composites possessed an electrochemical capacitance that was higher than that of each individual component due to synergistic effects. The NiCo₂O₄@Au@MnO₂ electrode has extremely high specific capacitance (1906.6 F g⁻¹ at 1 A g⁻¹) and excellent cycling stability (92.5% after 10,000 cycles) in a three-electrode system with 6M KOH electrolyte. Furthermore, the performance of an asymmetric supercapacitor of NiCo₂O₄@Au@MnO₂//AC was further evaluated, and the energy density was 98.3 Wh kg⁻¹ at a power density of 0.8 W kg⁻¹. The excellent electrochemical performance of such nanoscale architecture electrodes provides a new route for developing high-performance supercapacitors with 3D multicomponent heterojunction core-shell structures.

Through a simple grinding procedure, MIL-53Fe@PDI, a novel Z-scheme photocatalytic material, was synthesized. MIL-53Fe showed minimal photocatalytic activity under visible light for the degradation of doxycycline hydrochloride. Upon composite formation with PDI (perylene-3,4,9,10-tetracarboxylic diimide), the photocatalytic performance of MIL-53Fe significantly improved. The improvement was credited to the effective separation of carriers enabled by the Z-scheme heterojunction of MIL-53Fe@PDI, which hinders the recombination of electrons and holes generated by light. MIL-53Fe@PDI was utilized to enhance the breakdown effectiveness of doxycycline hydrochloride by triggering peroxymonosulphate in the presence of visible light. Thorough examinations were carried out to analyse how the amount of peroxymonosulphate, the concentration of doxycycline hydrochloride, various inorganic anions, and natural organic matter impact the activation of peroxymonosulphate for the degradation of doxycycline hydrochloride. Experiments involving radical quenching and analysis using electron paramagnetic resonance verified the activation mechanism of MIL-53Fe@PDI with peroxymonosulphate, indicating the significant involvement of sulphate and superoxide radicals in the degradation of doxycycline hydrochloride. Predictions of potential susceptible locations and routes of doxycycline hydrochloride were made using density functional theory calculations utilizing the Fukui function and UPLC-MS. Toxicity Estimation Software Tool indicated a gradual reduction in toxicity during the degradation of doxycycline hydrochloride. This study presents an effective and environmentally friendly approach for treating antibiotic wastewater.

Chronic wounds characterized by prolonged inflammation and persistent infection pose a significant burden to global healthcare systems. Currently, antibiotics and non-steroidal anti-inflammatory drugs (NSAIDs) are administered to patients. Prolonged use of antibiotics is severely discouraged owing to the rapid rise in antimicrobial resistance, and the use of NSAIDs can also increase the risk of infection. Thus, the discovery of novel therapeutics for chronic wounds is crucial. Antimicrobial peptides (AMPs) are an emerging class of therapeutics, which are effective and has no known mechanism of inducing resistance. Anti-inflammatory peptides (AIPs) are another class of therapeutic peptides that can reduce inflammation by eliciting anti-inflammatory cytokine response. A single peptide possessing both AMP and AIP activities can be an ideal therapeutic for the treatment of chronic wounds. However, the discovery of peptides with multiple properties via experimental testing is a daunting task. In this work, we propose a classification framework using machine learning for the identification of wound healing peptides (WHPs) i.e., which possess both AMP and AIP activities. The proposed framework uses XGBoost algorithm with amino-acid composition, sequence analysis and physicochemical properties as feature representation methods (FRMs) to develop binary classifiers. The model developed by combining all the three FRMs, resulted in the highest accuracy of 93.3 and 76.2% for AMP and AIP classifications, respectively. An easy-to-use freely accessible web tool (WHP-Pred) has also been developed.

In recent decades, massive exudation of heavy metals into natural water bodies has become prevalent world wide, posing threat to the environment, individuals and their well-being. Owing to its prolonged half-life and non-biodegradability, potential accumulation of heavy metals can cause serious health problems. Several cutting-edge diagnostic methods are being utilized for the assay of heavy/toxic metals. Certainly, these methods hold some limitations, such as requirement for extortionate devices and strenuous operations that can only be carried out in laboratories. This led to the emergence of detection methods based on sensors. Among various breakthroughs, paper-based analytical devices as well as paper-based microfluidic devices have turned up as one of the economical, convenient, easily disposable and portable substitutes for on-site detection. This study discusses the current analytical methods and paper-based devices used for heavy metal detection in the first phase followed by the discussion on comparative analysis of various analytical methods. In addition, there are techniques for heavy metal detection, which use substrates like paper, polydimethylsiloxane, etc. using colorimetric, fluorescence or electrochemical sensing, have also been discussed. The development of programmable paper-based microfluidic devices has been emphasized in the second phase of the discussion. Finally, the future progressions and developments in this field have also been proposed.