Degradation Test Research Articles

Physical, Chemical, and Mechanical Characterization of Coated Date Palm Leaf Fiber from the Middle Region of Iraq for Potential in Civil Engineering Application

Date palm leaf fibers are suitable for engineering applications due to their availability, inexpensiveness, and ecofriendliness. However, there is a risk of biodegradation in the long term. This paper explores date palm leaf fiiber (DPL) properties and the protection of the fibers from biodegradation to enhance their lifespan. To this end, two coating materials (bitumen and polyurethane) were used separately. Physical and mechanical tests were conducted to determine the most effective material to coat the DPL fibers. To comprehensively assess the performance of the coated fibers, their morphology was examined via microstructure analysis using scanning electron microscopy (SEM) and energy dispersive X-ray analyses (EDX) tests. This analysis encompasses their material properties, chemical composition, water absorption, and degradation, providing a thorough understanding of the protective coatings’ impact on the DPL fibers. The tensile strength test results revealed that the maximum tensile strength of the bitumen coated date palm fiber (DPLB) is 7.4 MPa. The tensile strength is two times greater than the polyurethane coated date palm leaf fiber (DPLP) and untreated date palm leaf fiber (UDPL). The results of the degradation test revealed that the weight loss percentage is equal to 45.5 and 25 in the case of the UDPL and DPLP fibers, and no loss in weight in the case of the DPLB fiber. Out of all the test results, bitumen is considered the best due to its ability to resist the attack of chlorides and sulfate ionspresent in groundwater on top of being cheap, simple, and efficient.

Proton Exchange Membrane Fuel Cell Stack Durability Prediction Using Arrhenius-Based Accelerated Degradation Model

To expand the applications of proton exchange membrane fuel cell (PEMFC) stacks, it is essential to address the issue of their short lifetime. Various studies are being conducted to improve this limitation, and efficient methods for verifying durability in a short period of time are required. This study presents a novel dynamic load cycling protocol designed to emulate the real-world driving conditions of commercial vehicles. This protocol was employed as an accelerated degradation test for PEMFC stacks under two elevated temperatures (65 and 80 °C), each conducted for 1000 h. A bi-exponential model, incorporating Arrhenius principles, was fitted to the degradation data. During this process, a mixed effects modeling approach was employed to distinguish between fixed and random effects within the model parameters. The activation energy was consistent across all cells and was thus designated as a fixed effect. Activation energy, which predominantly affects the long-term durability of PEMFC stacks, was estimated as 0.808 eV. By applying this estimated value to the Arrhenius equation, we calculated the acceleration factors for the degradation of fuel cell performance. Specifically, the rate of voltage degradation was found to be approximately 1.516 times faster at 65 °C and 4.923 times faster at 80 °C, compared to the standard operating temperature of 60 °C. Additionally, Monte Carlo simulations were conducted to predict the failure-time distribution under normal use conditions, estimating a median lifetime of 3884 h, which corresponds to 155,360 km of driving. This methodology offers a reliable and time-efficient framework for assessing PEMFC durability, with significant implications for reducing testing costs and accelerating the development of hydrogen fuel cell technology.

Optimal design of multivariate accelerated degradation test based on game theory

ABSTRACT Optimal design of the accelerated degradation test plays an important role in improving the reliability assessment accuracy of products. The commonly used optimal design methods of accelerated degradation tests are mainly based on a single performance degradation characteristic. When considering multiple-performance degradation characteristics, there is a problem that the resulting test plans cannot be unified. To solve the problem, a multivariate accelerated degradation test optimization method is presented based on game theory in this work. The accelerated degradation models are established with the Wiener process as the degradation model assumption, and the correlation is described by the Copula function. The optimization model is established with the objective function of maximizing the Fisher information matrix determinant for each degradation model. Based on game theory, the optimization model solution problem is transformed into a cooperative game problem, and the optimal test plan is obtained by maximizing the benefit function. Finally, the effectiveness of the proposed method is verified by an example of O-rings.

Biodegradable PLA films incorporating GO‐ZnO hybrid and Mentha Longifolia oil: Fabrication and characterization

AbstractThe study investigates the effects of graphene oxide/zinc oxide (GO‐ZnO) nanohybrids, combined with Mentha longifolia essential oil, on the mechanical, UV resistance, antibacterial, and rheological properties of polylactic acid (PLA). GO‐ZnO nanohybrids were prepared at ZnO‐to‐GO ratios of 1:1 and 2:1 and incorporated into PLA at various concentrations. The addition of GO‐ZnO significantly enhanced the tensile strength and modulus of PLA composites due to strong interactions between PLA and the functionalized nanohybrids. Hydrolytic degradation tests revealed accelerated PLA degradation with GO‐ZnO, attributed to the catalytic effects of ZnO. Rheological analysis showed reduced elasticity with higher nanohybrid content, attributed to thermal degradation. UV absorption tests demonstrated improved UV protection with GO‐ZnO and essential oil. Antibacterial tests indicated higher inhibition percentages against E. coli and Listeria, highlighting a synergistic antibacterial effect of the hybrid system. These findings suggest PLA/GO‐ZnO/oil composites are promising candidates for antibacterial packaging applications.Highlights PLA hydrolytic degradation enhanced by GO‐ZnO nanohybrids, M. longifolia oil. GO‐ZnO and M. longifolia oil catalyze PLA thermal degradation during scission. PBS mechanical properties improved via GO‐ZnO interaction with PLA and oil. GO‐ZnO and M. longifolia oil provide synergistic antibacterial effects in PLA. Thermal degradation of PLA with GO‐ZnO and oil analyzed through rheology.

An In-Plane Heterostructure Ni3N/MoSe2 Loaded on Nitrogen-Doped Reduced Graphene Oxide Enhances the Catalyst Performance for Hydrogen Oxidation Reaction

Non-noble metal electrocatalysts for the hydrogen oxidation reaction (HOR) that are both highly active and low-cost are essential for the widespread use of fuel cells. Herein, a simple two-step method for creating an in-plane heterostructure of Ni3N/MoSe2 loaded on N-doped reduced graphene oxide (Ni3N/MoSe2@N-rGO) as an effective electrocatalyst for the HOR is described. The process involves hydrothermal treatment of the Ni and Mo precursors with N-doped reduced graphene oxide, followed by the annealing with urea. The Ni3N/MoSe2@N-rGO catalyst exhibits high activities for the HOR, with current densities of 2.15 and 3.06 mA cm−2 at 0.5 V vs. the reversible hydrogen electrode (RHE) in H2-saturated 0.1 M KOH and 0.1 M HClO4 electrolytes, respectively, which is comparable to a commercial 20% Pt/C catalyst under similar experimental conditions. Furthermore, the catalyst demonstrates excellent durability, maintaining its performance during accelerated degradation tests for 5000 cycles. This work offers a practical framework for the designing and preparing of non-precious metal electrocatalysts for the HOR in fuel cells.

Effect of Volumetric Energy Density on the Evolution of the Microstructure and the Degradation Behavior of 3D-Printed Fe-Mn-C Alloys from Water-Atomized Powders

Additive manufacturing of metals opens new doors for innovation in custom-based productions in a wide range of fields, including medicine, even if it introduces new challenges that need to be addressed to guarantee the properties are equal to or superior to those of conventional fabrication processes. In this research, porous, biodegradable Fe-Mn-C alloys were fabricated using a 3D printing technique with four different printing energy densities ranging from 62.5 to 125.0 J/mm3. The effect of printing energy density on the microstructure and degradation behavior was investigated. Lower energy densities resulted in higher pore density and the presence of unmelted powder particles, while the alloy printed at 104.2 J/mm3 exhibited the lowest pore density and the smallest grain size. Degradation tests revealed that the highest pore density in the sample printed at 62.5 J/mm3, and the lowest grain size in the sample printed at 104.2 J/mm3 contributed to faster degradation rates. The alloy printed at the highest energy density, 125.0 J/mm3, demonstrated the largest grain size and the slowest degradation rate. Energy-dispersive spectroscopy and Fourier transform infrared spectroscopy analyses identified manganese carbonate as the primary degradation product, with calcium phosphate forming as a secondary product. These findings provide a significant understanding of the relationship between printing parameters, microstructure, and degradation behavior, which are essential for optimizing the performance of Fe-Mn-C alloys in biodegradable material applications.

Development and Validation of Reliability Testing Methods for Insulation Systems in High-Voltage Rotating Electrical Machinery on Ships

Lloyd’s Register became the first classification society to mandate reliability testing for insulation degradation in rotating electrical machinery. As the maritime industry shifts toward eco-friendly practices, high-voltage rotating electrical machinery on ships increasingly features higher voltages and larger capacities. However, incidents involving insulation systems have also become more frequent. Additionally, testing facilities with the necessary equipment to perform such reliability tests are lacking, and standardized testing methods are yet to be established. This study proposes test items, methods, and evaluation criteria for the reliability testing of high-voltage rotating electrical machinery. The testing methods are broadly categorized into four types: thermal, electrical, multifactor, and thermomechanical degradation reliability testing. The proposed methods were validated by conducting long-term testing over approximately one year. Key results showed a breakdown time of 7056 h in thermal evaluation, 5040 h in electrical evaluation, and 258.5 d in multifactor evaluation, as well as a 63rd percentile value of 245.7 h in thermomechanical evaluation, all of which fulfill the required criteria. The study offers practical guidelines for ensuring the durability and safety of high-voltage electrical machinery, aligning with the sustainability and safety goals of the maritime industry.

Degradation Behavior and Mechanical Properties of Porous Biodegradable FeMnC Alloys Produced by Powder Metallurgy for Biomedical Applications

The advent of biodegradable implants represents a landmark orientation in the biomedical field toward a new generation of medical devices, offering improved patient outcomes, and eliminating the need for subsequent surgeries. FeMn alloys are well‐established as promising candidates for such applications. This study analyzes the microstructure, mechanical properties, and degradation behavior of FeMnC alloys produced via pressing and sintering process using water‐atomized FeMnC powder. To investigate the impact of pore size and volume fraction on the mechanical properties and degradation rates, two groups of FeMnC samples were prepared, one compacted at 600 MPa (CP 600) and the other at 700 MPa (CP 700). In addition, pure Fe samples compacted at 600 MPa and prepared using the same methodology were used as a reference. Chemical analysis carried out on both the pre‐alloyed powder and the resulting sintered samples (CP 600 and CP 700) revealed a significant reduction in the amount of Mn, O, and notably C after sintering. The pure Fe group showed the greatest mechanical strength with an average tensile rupture strength of 446 ± 24 MPa. Among the three groups, CP 600 exhibited the highest degradation rate (−0.339 ± 0.057 mmpy) after 14 days of static immersion degradation test in modified Hanks' solution, demonstrating a degradation behavior characterized by mass gain.

The Influence of Iron Particles and Polyethylene Glycol on Selected Properties of Polylactide-Based Composites.

This article presents the characteristics of composites comprising polylactide combined with iron powder, from 1 to 10 wt.%, and nanoiron powders with a mass fraction from 0.1 to 1.0 wt.%, along with polyethylene glycol. A total of nine composites were prepared, with three variations each: polylactide with iron powder, polylactide with nanoiron powder, and polylactide with micro- and nanoiron powder combined with polyethylene glycol. The samples underwent mixing, extrusion, and pressing processes. To assess the properties of the resultant composite samples, ultimate tensile tests, Shore hardness tests, fracture surface observations, degradation tests in 0.9% saline solution, and DSC analyses were conducted. The findings revealed that nanoiron powder incorporated into the polylactide matrix demonstrates better tensile properties, both strength and elongation, compared to those incorporating micrometric-iron powder only. However, both iron powder additions led to a decrease in the total elongation of neat polylactide acid except for the composite with 1% nanoiron. Furthermore, all samples with polyethylene glycol addition show a lower Young's modulus compared to neat PLA. In general, the microiron powder decreases the Young's modulus of PLA composites, whereas the nanoiron powder slightly increases the Young's modulus of these samples. Polyethylene glycol, a biocompatible substance, emerged as a suitable candidate for enhancing the adhesion of iron particles and improving the strength and elongation properties of the tested composites. Also, fracture surface analysis of the tensile samples suggests using fine nanoiron particles instead of coarse ones to improve the mechanical properties due to the stronger bonding of nanoiron particles to the PLA matrix.

A photocatalytic superhydrophobic coating with p-n type BiOBr/α-Fe2O3 heterojunctions applied in NO degradation.

Coal combustion generates soot-type air pollution, and NO, as a typical pollutant, is the main haze-causing pollutant. The degradation of NO by means of photocatalytic superhydrophobic multifunctional coatings is both durable and economical. The precipitation method was employed to create a p-n type BiOBr/α-Fe2O3 photocatalytic binary system. BiOBr/α-Fe2O3 nanoparticles were combined with polydimethylsiloxane (PDMS) in a butyl acetate solution to produce a BiOBr/α-Fe2O3/PDMS/butyl acetate emulsion, and photocatalytic superhydrophobic coatings were then prepared using a one-step cold-spraying method. Photocatalytic oxidation experiments were conducted using a low concentration of NO as the targeted degradant. The results indicate that BiOBr/α-Fe2O3 photocatalytic heterojunctions were successfully prepared with NO removal up to 65%, indicating that the formation of p-n type heterojunctions enhances the light absorption range and improves the separation of photogenerated charge carriers. Furthermore, when the mass ratio of photocatalytic material to PDMS is 30 : 1, the photocatalytic superhydrophobic coating exhibits optimal performance, attaining a contact angle of 159.55° and NO degradation rate of 70.9%. The study also found that the photocatalytic superhydrophobic coating remained stable after undergoing cyclic degradation, acid and alkali resistance tests, and self-cleaning tests. The mechanism of photocatalytic superhydrophobic coatings was further explored, which provided new insights and a theoretical foundation for the development of self-cleaning urban environments.

Synergistic design of a graphene oxide-mediated polyaniline/α-Fe2O3 ternary heterostructure: advancing photocatalytic degradation and adsorption efficiency.

With the growing threat of organic pollutants in water bodies, there is an urgent need for sustainable and efficient water decontamination methods. This research focused on synthesizing a novel Z-scheme ternary heterostructure composed of graphene oxide (GO)-mediated polyaniline (PANI) with α-Fe2O3 and investigated its potential in brilliant green (BrG) and ciprofloxacin (CIP) degradation tests under visible light. The ternary composite demonstrated exceptional photocatalytic activity, with the optimized 10%PANI/GO/α-Fe2O3 (10PGF) photocatalyst achieving 99.8% degradation of BrG in 25 min and 93% degradation of CIP in 90 min of irradiation. The 10PGF composite achieved rate constants of 0.222 min-1 for BrG and 0.0295 min-1 for CIP. The rate constant for BrG degradation was 15 and 10 times faster than that for PANI and α-Fe2O3, respectively, while CIP was degraded 8.9 and 6.1 times faster. The degradation of the pollutants was facilitated by both O2˙- and ˙OH, as confirmed by capturing active species, a nitroblue tetrazolium test and use of a PL terephthalic acid probe. The proposed Z-scheme mechanism elucidated charge carrier movements and active species involvement, revealing the enhanced photocatalytic performance of the ternary composite. The 10PGF ternary composite demonstrated exceptional recyclability over five repeated cycles, with XRD analysis confirming no structural changes in the material. Moreover, adsorption studies were also performed, which showed a strong correlation (R2 = 0.974) with Langmuir isotherms and that pseudo-second order kinetics was followed.

Functionalized Periosteum-Derived Microsphere-Hydrogel with Sequential Release of E7 Short Peptide/miR217 for Large Bone Defect Repairing.

Large bone defects are still a persistent challenge in orthopedics. The availability limitations and associated complications of autologous and allogeneic bone have prompted an increasing reliance on tissue engineering and regenerative medicine. In this study, we developed an injectable scaffold combining an acellular extracellular periosteal matrix hydrogel with poly(d,l-lactate-co-glycol-acetate) microspheres loaded with the E7 peptide and miR217 (miR217/E7@MP-GEL). Characterization of the composites included morphological analysis by scanning electron microscopy, degradation and swelling tests, invitro and invivo biological evaluation, and the biological activity evaluation of mesenchymal stem cells (MSCs) through their effects on cell recruitment, proliferation, and osteogenic differentiation. The designed hydrogels demonstrated good physical and chemical properties that are cytocompatible and suitable for cell recruitment. Invitro studies confirmed the high biological activity of the release agent, which markedly enhanced the proliferation and osteogenic differentiation of MSCs. Invivo application to a rat model of a femur defect exhibited a significant increase in bone volume and density over 7 weeks, resulting in enhanced bone regeneration. Acellular periosteum-based hydrogels combined with the E7 peptide and miR217-loaded poly(d,l-lactate-co-glycol-acetate) microspheres can promote effective bone regeneration through the recruitment, proliferation, and osteogenic differentiation of MSCs, which provides a promising approach for the treatment of large bone defects.

Synthesis and Characterization of Sodium Carboxymethyl Cellulose/Chitosan/Polyvinyl Alcohol Hydrogels to Removal Ionic Dyes and Their Biodegaration

ABSTRACTHydrogels from polyvinyl alcohol (PVA), sodium carboxymethyl cellulose (CMC), chitosan (CS) were syntheised via gamma irradiation at different radaition dose; 0, 2.5, 5, 10, and 20 kGy. The syntheized hydrogels were chataerized by gelation (%), swelling (%), XRD, and SEM to confirm the hydrogel formations. The hydrogels were used to remove dyes of direct blue 1 (DB1), methylene blue (MB) from their aqueous soltions. The effect of contact time, feeding intial concentration and temperature were investigated. The adsorption of kinetics models such pseudo first‐order, pseudo second‐order, and Bangham were studied. The results of kinetics invetsiation showed that DB1 obeys pseudo second‐order, while MB obeys pseudo first‐order. Moreover, the adsorption iostherms of Langmuir isotherm model, Freundlich, Redlich–Peterson isotherm, Sips isotherm, Hill isotherm were applied. The outcome results referred that both of DB1 and MB obey Langmuir model. Further, the Soil degradability test of pure hydrogels and hydrogels‐adsorbed DB1 and hydrogels‐adsorbed MB was carried out by burial under soil for 14 days. The results showed the pure hydrogels exposed rapid soil degradability than hydrogels‐adsorbed DB1 and hydrogels‐adsorbed MB. Furthermore, water‐holding capacity and water retention of sandy soils of hydrogels were studied. The results of water‐holding capacity and water retention showed that the hydrogels that prepared at 20 kGy is highest one than that prepared at 2.5 kGy is the lowest one.

Synthesis of Cellulose Straw and Rice Husk as Raw Materials for Bioplastic Production

The development of environmentally friendly materials such as bioplastics is a solution to reduce the negative impact of conventional plastics on the environment. This study presents a novel approach by utilizing hemicellulose extracted from rice straw and husks—abundant agricultural waste materials—as the main raw materials for bioplastic production. Hemicellulose was extracted using the alkalization method, and its characterization was carried out through FTIR analysis to identify typical polysaccharide functional groups. The results of the analysis showed the presence of O-H, C-H, and C-O-C groups, which indicate the glycosidic structure of hemicellulose, as well as indications of residual lignin with C=C groups. The resulting hemicellulose was then processed into bioplastics with the addition of plasticizers and reinforcing materials, incorporating glycerin, CMC, and TiO₂ to enhance mechanical properties and biodegradability. Mechanical and degradation tests demonstrated superior performance, highlighting the synergy between these additives. This study provides an innovative strategy for transforming agricultural waste into high-value bioplastics, contributing to sustainability and advancing green material technology.

Hybrid Hydrogel Supplemented with Algal Polysaccharide for Potential Use in Biomedical Applications.

Hydrogels are a viable option for biomedical applications due to their biocompatibility, biodegradability, and ability to incorporate various healing agents while maintaining their biological efficacy. This study focused on the preparation and characterization of novel hybrid hydrogels enriched with the natural algae compound Ulvan for potential use in wound dressings. The characterization of the hydrogel membranes involved multiple methods to assess their structural, mechanical, and chemical properties, such as pH measurements, swelling, moisture content and uptake, gel fraction, hydrolytic degradation, protein adsorption and denaturation tests, rheological measurements, SEM, biocompatibility testing, and scratch wound assay. The hydrogel obtained with a higher concentration of Ulvan (1 mg/mL) exhibited superior mechanical properties, a swelling index of 264%, a water content of 55%, and a lower degradation percentage. In terms of rheological properties, the inclusion of ULV in the hydrogel composition enhanced gel strength, and the Alginate + PVA + 1.0ULV sample demonstrated the greatest resistance to deformation. All hydrogels exhibited good biocompatibility, with cell viability above 70% and no obvious morphological modifications. The addition of Ulvan potentiates the regenerative effect of hydrogel membranes. Subsequent studies will focus on encapsulating bioactive compounds, investigating their release behavior, and evaluating their active biological effects.

Optimal time plan for accelerated degradation testing based on the inverse Gaussian process

This paper addresses the optimal design problem for constant-stress accelerated degradation tests using inverse Gaussian (IG) process models. Unlike previous studies that primarily focussed on optimizing stress levels and sample sizes, this research uniquely emphasizes the critical role of measurement timing as a design variable. We investigate D-, A-, and V -optimal designs for IG processes, both with and without random effects. Our study derives analytical solutions for optimal measurement time schedules in IG processes characterized by linear degradation paths and provides numerical solutions for those with nonlinear degradation paths. To streamline the search for optimal time schedules, we employ a lower-dimensional parameterization method that mitigates the substantial computational burden. This approach facilitates the generation of multiple measurement times using only a limited number of design variables. The numerical results highlight the significant impact of optimal time scheduling on enhancing the efficiency and effectiveness of accelerated degradation test designs.

Synthesis and characterisation of calcium magnesium aluminate nanomaterials using neem plant extract: its photocatalytic and supercapacitor application

ABSTRACT The synthesis of Calcium Magnesium Aluminate nanoparticles (CMA NPs) using Azadirachta indica (neem) leaf extract is presented in this paper. The photochemical and electrochemical properties of green CMA NPs also studied. PXRD data indicate a hexagonal phase with space group P63/mmc with average crystallite size of approximately 19.05 nm. SEM analysis shows a homogeneous, flower-like morphology and UV-DRS investigations reveal an energy gap (Eg) of 4.377 eV. The dye degradation tests on Fast Orange (FO) and Fast Blue (FB) dyes under UV (0–120 min) show the highest photocatalytic activity for FO. Cyclic Voltammetry (CV) in 1 M KOH electrolyte shows excellent redox potential with a graphite electrode. Electrochemical Impedance Spectroscopy (EIS) reveals reduced charge transfer resistance, and enhanced electrochemical performance. Specific capacitance values were 48 Fg−1. Galvanostatic charge-discharge tests confirm excellent capacitance for battery and supercapacitor applications.

Pt2Gd Alloy Nanoparticles from Organometallic Pt and Gd Complexes and Hollow Mesoporous Carbon Spheres: Enhanced Oxygen Reduction Reaction Activity and Durability.

Pt2Gd alloy nanoparticles supported in hollow mesoporous carbon spheres (HMCS; Pt2Gd/HMCS) were successfully prepared by the thermal reduction of organometallic Pt and Gd complexes without oxygen atoms supported in the pores of HMCS. The structures of Pt2Gd alloy nanoparticles were fully characterized by TEM, HAADF-STEM-EDS, XRD, XAFS, and XPS, suggesting the formation of uniform Pt2Gd alloy nanoparticles with an average particle size of 5.9 nm. Pt2Gd/HMCS showed superior oxygen reduction reaction activity (2.4 times higher mass-specific activity to Pt nanoparticles on HMCS (Pt/HMCS)) and remarkable durability even after the 100,000 cycles of accelerated degradation tests compared to Pt/HMCS and a commercial Pt/C catalyst. The structure of the Pt2Gd alloy nanoparticles after initial aging and the durability tests suggested that the Pt2Gd core-Pt shell structure with a particle size similar to the pore size of HMCS was stably formed inside the porous structure of HMCS and maintained under the oxygen-reduction working conditions.

Construction of a recombinant Bacillus subtilis strain expressing SpaA and CbpB of Erysipelothrix rhusiopathiae and evaluation of the strain immunogenicity in a mouse model

To construct a recombinant Bacillus subtilis strain expressing SpaA and CbpB of Erysipelothrix rhusiopathiae for oral administration, we constructed the recombinant plasmid pDG1730-CBJA by fusion PCR and seamless cloning. The plasmid was introduced into B. subtilis KC strain by natural transformation, and the recombinant strain KC-spaA-cbpB was screened out on the plate containing spectinomycin (sper) and confirmed by PCR and starch degradation test. The SpaA and CbpB expressed by KC-spaA-cbpB were detected by Western blotting and indirect immunofluorescence assay, and the genetic stability of the recombinant strain in mice was determined. The plasmid pMAD-∆sper with knockout of sper was constructed and transformed into KC-spaA-cbpB. The sper-deleted mutant strain KC-spaA-cbpB: : ∆sper was screened and identified, and its immunogenicity in a mouse model was evaluated by oral immunization. The results showed that the recombinant strain KC-spaA-cbpB was stable in mice, expressing SpaA on the cell surface and CbpB on the spore surface. KC-spaA-cbpB: : ∆sper expressed SpaA and CbpB. The mice vaccinated with the spores of KC-spaA-cbpB: : ∆sper had higher levels of SpaA and CbpB-specific IgG in the serum that those vaccinated with the wild-type spores 42 days after vaccination by gavage (P < 0.01). The protective rate of mice immunized with the recombinant spores was 67.5%. The results indicated that a recombinant B. subtilis strain expressing SpaA and CbpB of E. rhusiopathiae was successfully constructed, and the recombinant strain laid a foundation for the development of oral live vector vaccines for swine erysipelas.

Synthesis of different types of calcium phosphates for the drug loading and releasing applications

Abstractβ‐tricalcium phosphate and various forms of hydroxyapatites (HAps) were produced through the wet chemical precipitation method, using calcium hydroxide, orthophosphoric acid, cow bone, and fish scale as raw materials. The synthesized samples underwent characterization through x‐ray diffraction, and their antimicrobial efficacy was assessed in powder form for gram‐positive Staphylococcus aureus bacteria as well as gram‐negative Escherichia coli bacteria. In vitro degradation tests were conducted using simulated body fluid after compressing the powdered samples into scaffolds and sintering at 900°C. These scaffolds were subsequently used to study drug loading and releasing over different periods. All scaffolds demonstrated strong loading capacities for amoxicillin (AMX) and ciprofloxacin (CIP), notably Rui bone HAp achieving 90.83% loading of AMX and cow bone HAp showing 98.73% loading of CIP. In contrast, both fluoride‐doped HAp types displayed significant AMX release, whereas Rui bone HAp showed the highest CIP release. The pH and conductivity of drugs and drug‐released SBF solution were examined after 21 days and 1 day, respectively.