Phase Content Research Articles

A Limited Evaluation of the Applicability of NACE MR0175/ISO 15156 H2S Limits to Supercritical CO2 Pipelines

In an earlier paper one of the authors raised the question of whether the hydrogen sulfide (H2S) partial pressure threshold of 0.05 psia (0.3 kPa) for cracking of steels from sulfide stress cracking is pertinent to dense phase carbon dioxide (CO2) systems in which there is no free gas phase. This paper presents a limited test of the pertinence of this threshold value in Supercritical CO2. Autoclave tests of four-point bend beam specimens of API 5L Grade X80 line pipe steel at 0.05 psia (0.3 kPa) and 0.20 psia (1.38 kPa) H2S were performed and the samples were examined after testing for cracking. In addition, the test conditions were modeled with the OLI Studio software to determine the H2S fugacities and H2S concentrations in the brine phase. No cracking was found after 30 d of exposure.

Behavior of free-standing atmospheric plasma sprayed Al2O3–Cr2O3 solid solution-based coatings under cyclic heating at 1000 °C

This paper investigates the cyclic heating behavior of free-standing atmospheric plasma sprayed Al2O3 - Cr2O3 coatings containing a solid-solution phase. The coatings are deposited on steels by spraying mechanically blended Al2O3 - Cr2O3 powder mixture with variable Cr2O3 content (2–6 wt%) in the feedstock. The tests are performed up to 50 cycles at 1000 °C temperature in a muffle furnace in a normal atmosphere. After each cycle, the weight gain of the coatings is measured, and the oxidation rate constant (Kp) for each material is estimated. The microstructure and phases of the coatings are studied by using scanning electron microscopy (SEM) and X-ray diffractometry (XRD) techniques respectively. The porosity and crack length are estimated by image analysis (Image J) technique. The hardness of the coatings is measured by Vickers microhardness tester. After 50 cycles, all the free-standing coatings are found to be intact without fragmentation. At higher cycles, the Al2O3 - Cr2O3 coatings form α-Al2O3 and (Al0.9Cr0.1)2O3 solid-solution phase only. The Al2O3 - Cr2O3 coatings gain much less weight than the pure Al2O3 coating due to the major presence of oxidation resistant α-Al2O3 phase in the former. However, among the Al2O3 - Cr2O3 coatings with an increase in Cr2O3 content, the Kp value tends to increase due to the high presence of metastable (Al1.8Cr0.05)2O3 solid-solution phase. On the other hand, the (AlxCr1-x)2O3 phase helps to reduce crack formation due to its high fracture toughness properties. With the highest amount of solid-solution phase content, the Al2O3-4 wt% Cr2O3 coating shows the highest fracture toughness among all. The micro-porosity of the coatings is increased with an increase in the heating cycle, and the coating hardness is reduced accordingly.

Mechanical properties and corrosion resistance improvement of TiAlSnMo alloys via Mo addition

In this paper, Ti-5Al-2.5Sn-xMo (TASxM, x = 0,5,10,15 wt%) alloys were designed and prepared. Phase compositon and microstructure analysis results indicate that the addition of Mo reduces the phase transition point of TASxM alloys, stabilizes more β phase to room temperature, and refines the α grains. The strength of the TASxM alloys exhibits a positive correlation with the increasing Mo content within 10 wt%, and the highest ultimate tensile strength (UTS) can be obtained in TAS10M (1260 MPa), which can be primarily attributed to the synergistic effects of phase transition, solid solution strengthening, and fine grain strengthening. Interestingly, the UTS of TAS15M unexpectedly decreases to 724 MPa, which is strongly influenced by the altered slip system numbers resulting from the β/α phase ratio. Even more intriguing is the observation of stress-induced martensitic transformation in the deformed TAS15M alloy, often resulting in a substantial influence on elongation. The corrosion resistance of the TASxM alloy has also been investigated through electrochemical experiments. The findings reveal that the corrosion resistance of the TASxM alloy is enhanced with the elevation of Mo content, peaking at TAS15M. This improved resistance is attributed to the augmented β phase content and the formation of protective MoO2 and MoO3 oxide films on the surface of alloy.

Characterization of bulk interior and fusion crust of Calama 009 L6 ordinary chondrite

AbstractFragment of Calama 009 L6 ordinary chondrite recovered in the Atacama Desert was chosen for a complex study of the bulk interior and the fusion crust by scanning electron microscopy (SEM) with energy‐dispersive spectroscopy (EDS), X‐ray diffraction (XRD), magnetization measurements, and Mössbauer spectroscopy. SEM demonstrated the presence of Fe‐Ni‐Co grains, troilite and chromite inclusions in both the bulk interior and the fusion crust as well as many veins with ferric compound. EDS showed variations in the Ni concentration within the metal grains and within one metal phase in the grain. XRD revealed some differences in the contents of various phases in the bulk interior and in the fusion crust. XRD indicated the presence of magnesioferrite in the fusion crust as well as the formation of goethite nanoparticles with the mean size of 9 nm in both the bulk interior and the fusion crust. Magnetization measurements demonstrated the ferrimagnetic–paramagnetic phase transition in chromite at 44 K and low values of the saturation magnetization moments (6.46 and 3.26 emu g−1 at 100 K) for the bulk interior and the fusion crust, respectively, due to the lack of Fe‐Ni‐Co alloy as a result of weathering. The Mössbauer spectra of the bulk interior and the fusion crust showed some differences in the number and relative areas of spectral components. The revealing of the Mössbauer spectral components related to 57Fe in the M1 and M2 sites in olivine and orthopyroxene as well as determining the Fe2+ occupations of these sites from XRD permitted us to estimate the temperature of equilibrium cation distribution for these silicates which are (i) 662 K (XRD) and 706 K (Mössbauer spectroscopy) for olivine and (ii) 893 K (XRD) and 910 K (Mössbauer spectroscopy) for orthopyroxene.

Simulation of anaerobic biodegradation process in a tubular bioreactor with a biofilm layer: Steady-state and unsteady-state conditions

In this paper, anaerobic biodegradation process in a tubular bioreactor with an inner biofilm layer for steady-state and unsteady-state conditions are simulated. The effects of various parameters including bioreactor diameter, fraction of active biomass transferred to liquid phase, and residence time of the liquid on bioreactor performance are examined. Simulations indicate that decreasing diameter of bioreactor leads to increasing degree of conversion of the substrate in liquid phase and decreasing dimensionless concentration of the substrate in biofilm. With an increase in the fraction of active biomass transferred to liquid, substrate concentrations in liquid and biofilm slightly vary. Increased residence time of the liquid phase results in the degree of conversion of substrate goes up, but substrate concentration in biofilm lowers a little. In addition, it is found that biomass concentration of liquid phase is boosted with decreased bioreactor diameter and increased residence time of liquid. A proportional-integral controller is designed and the tuned parameters of KP=−0.131 and KI=0.02 are obtained using genetic algorithm. It is observed that controller regulate well the degree of conversion of the substrate within 120 s for both servo and regulatory modes.

Two deep learning methods in comparison to characterize droplet sizes in emulsification flow processes

AbstractFor reliable supervision in multiphase processes, the droplet size represents a critical quality attribute and needs to be monitored. A promising approach is the use of smart image flow sensors since optical measurement is the most commonly used technique for droplet size distribution determination. For this, two different AI-based object detection methods, Mask RCNN and YOLOv4, are compared regarding their accuracy and their applicability to an emulsification flow process. Iterative optimization steps, including data diversification and adaption of training parameters, enable the models to achieve robust detection performance across varying image qualities and compositions. YOLOv4 shows better detection performances and more accurate results which leads to a wider application window than Mask RCNN in determining droplet sizes in emulsification processes. The final droplet detection model YOLOv4 with Hough Circle (HC) for feature extraction determines reliable droplet sizes across diverse datasets of liquid-liquid flow systems (disperse phase content 1–15 vol.-%, droplet size range 5–150 μm). Evaluating the adjustment of Confidence Scores (CS) ensures statistical representation of even smaller droplets. The droplet detection performance of the final YOLOv4 model is compared with a manual image processing method to validate the model in general as well as its accuracy and reliability. Since YOLOv4 in combination with Hough Circle (HC) shows an accurate and robust detection and size determination, it is applicable for online monitoring and characterization of various liquid-liquid flow processes. Graphical abstract

Effects of Cr and Mo content on the microstructure and properties of Fe-based amorphous composite coatings by laser cladding

In this study, we successfully produced Fe-based amorphous composite coatings on the surface of 45 steel using laser cladding technology, and the impact of the relative content of Cr and Mo elements on the microstructure, hardness, and wear resistance of composite coatings has been investigated. The results show that the microstructure of the coating changes from dendrite to amorphous nanocrystalline when the content of Cr and Mo is 20 and 15 wt. %, respectively. However, when the Mo element continues to be added, elemental segregation will be caused, resulting in a large number of brittle Fe–Cr–Mo intermetallic compounds and MoSi2 ceramic phases in the coating. Therefore, the appropriate element ratio can not only increase the amorphous phase content in the coating but also prevent elemental segregation. Among the three types of amorphous composite coatings studied, the Fe45Cr20Mo15B10Si10 (wt. %) composite coating exhibited the most favorable performance, primarily due to its highest amorphous content (43.33%). Through the interaction of the amorphous phase, α-Fe, Fe–Cr solid solution, and a small proportion of intermetallic compounds, this coating achieved a hardness of 1282.8 HV0.2, approximately five times that of the 45 steel substrate, and demonstrated superior wear resistance.

Effect of different Zn/Mg ratios on the uniformity of 7185+TiB2/TiC aluminum alloy thick plates

Three types of 7185+TiB2/TiC aluminum matrix composites with different Zn/Mg ratios were prepared in this work through a water-cooled copper casting process. The effects of Zn/Mg ratio on the microstructure and mechanical properties of 20-mm-thick composites were studied by optical microscopy, electron back scattering diffraction, transmission electron microscopy, and tensile mechanical testing. The results showed that the addition of appropriate TiB2/TiC particles refined the as-cast microstructure of the alloy, and with a decrease in Zn/Mg ratio, the grain size distribution became more uniform, the crystalline phase content gradually increased, and the uniformity of the alloy increased. After aging, as the Zn/Mg ratio decreased, the size of the precipitated phase decreased, and the strengthening effect of the alloy improved. The tensile strengths of the surface layer, 1/4 layer, and center position of the A3 alloy were 558, 568, and 572 MPa, respectively. The strength difference among the different thickness layers was the smallest, and the elongation rate was greater than 12%, resulting in the best uniformity.

Steady State and Time-Resolved Fluorescence Spectroscopy of Cinchonine Dication in Sodium Dodecylsulphate Micellar System.

This paper reports the influence of surface charge of the micelles on to the photophysical properties of a cinchonine dication (C2+) fluorophore in anionic, sodium dodecylsulphate (SDS), surfactant at premicellar, micellar and post-micellar concentrations in aqueous phase at room temperature. The magnitude of edge excitation red shift (EERS) in the fluorescence maximum of C2+ in bulk water solution is 1897cm- 1 whereas, in the case of SDS it is observed to be 1984cm- 1. The fluorescence decay curve of C2+ fits with multi exponential functions in the micellar system. The increase in lifetime of C2+ in SDS has been attributed to the increase in radiative rate due to the incorporation of C2+ at the micelle -water interface. The value of dynamic quenching constant determined is 16.9 M- 1. The location of the probe molecule in micellar systems has been justified by a variety of spectral parameters such as dielectric constant, ET (30), viscosity, EERS, average fluorescence decay time, radiative and non-radiative rate constants. All experimental results suggest that the C2+ molecule binds strongly with the SDS micelles and resides at micellar-water interface. The binding constant (Kb) calculated (3.85 × 105 M- 1) for C2+ in SDS revealed that the electrostatic forces mediate charge probe-micelle association.

Influence of heat treatment on the microstructure evolution and corrosion performance of biodegradable Zn-Mg alloys

Zinc and zinc-based alloys have garnered increasing attention as biodegradable materials due to their excellent mechanical properties, lower degradation rates compared to magnesium, and favorable biocompatibility. This study investigates the impact of homogenization treatment on the microstructure and corrosion behavior of Zn-Mg alloys using scanning electron microscopy, X-ray diffraction, hardness testing, and accelerated corrosion immersion tests. The results reveal that homogenization treatment induces the fusion of eutectic cells within the alloys, causing significant morphological alternations in the eutectic structure and varying proportions of the Mg2Zn11 phase, These changes notably affect material properties. The raised content of Mg2Zn11 phase in the eutectic structure correlates with higher hardness but reduced corrosion resistance, whereas the reduced Mg2Zn11 phase content leads to enhanced corrosion resistance. Furthermore, in-situ corrosion observations demonstrate that corrosion initiates at the eutectic phase, with corrosion pits forming due to the ion release as corrosion progresses, leading to gradual enlargement of the corrosion pits. In summary, this study provides comprehensive insights into the microstructural changes in Zn-Mg alloys and their impact on corrosion resistance, offering valuable references for their engineering applications.

Influence of Menstrual Cycle and Oral Contraceptive Phases on Bone (re)modelling Markers in Response to Interval Running

To explore how sex hormone fluctuations may affect bone metabolism, this study aimed to examine P1NP and β-CTX-1 concentrations across the menstrual and oral contraceptive (OC) cycle phases in response to running. 17β-oestradiol, progesterone, P1NP and β-CTX-1 were analysed pre- and post-exercise in eight eumenorrheic females in the early-follicular, late-follicular, and mid-luteal phases, while 8 OC users were evaluated during the withdrawal and active pill-taking phases. The running protocol consisted of 8 × 3min treadmill runs at 85% of maximal aerobic speed. 17β-oestradiol concentrations (pg·ml−1) were lower in early-follicular (47.22 ± 39.75) compared to late-follicular (304.95 ± 235.85;p = < 0.001) and mid-luteal phase (165.56 ± 80.6;p = 0.003) and higher in withdrawal (46.51 ± 44.09) compared to active pill-taking phase (10.88 ± 11.24;p < 0.001). Progesterone (ng·ml−1) was higher in mid-luteal (13.214 ± 4.926) compared to early-follicular (0.521 ± 0.365; p < 0.001) and late-follicular phase (1.677 ± 2.586;p < 0.001). In eumenorrheic females, P1NP concentrations (ng·ml−1) were higher in late-follicular (69.97 ± 17.84) compared to early-follicular (60.96 ± 16.64;p = 0.006;) and mid-luteal phase (59.122 ± 11.77;p = 0.002). β-CTX-1 concentrations (ng·ml−1) were lower in mid-luteal (0.376 ± 0.098) compared to late-follicular (0.496 ± 0.166; p = 0.001) and early-follicular phase (0.452 ± 0.148; p = 0.039). OC users showed higher post-exercise P1NP concentrations in withdrawal phase (61.75 ± 8.32) compared to post-exercise in active pill-taking phase (45.45 ± 6;p < 0.001). Comparing hormonal profiles, post-exercise P1NP concentrations were higher in early-follicular (66.91 ± 16.26;p < 0.001), late-follicular (80.66 ± 16.35;p < 0.001) and mid-luteal phases (64.57 ± 9.68;p = 0.002) to active pill-taking phase. These findings underscore the importance of studying exercising females with different ovarian hormone profiles, as changes in sex hormone concentrations affect bone metabolism in response to running, showing a higher post-exercise P1NP concentrations in all menstrual cycle phases compared with active pill-taking phase of the OC cycle.

3D Printed Drug Delivery Systems in Action-Magnetic Resonance Imaging and Relaxometry for Monitoring Mass Transport Phenomena.

The hypothesis of the study was that (1) 3D printed drug delivery systems (DDS) could be characterized in situ during drug release using NMR/MRI techniques in terms of mass transport phenomena description (interfacial phenomena), particularly for systems dealing with two mobile phases (e.g., water and low molecular weight liquid polymer); (2) consequently, it could be possible to deduce how these interfacial mass transport phenomena influence functional properties of 3D printed DDS. Matrix drug delivery systems, prepared using masked stereolithography (MSLA), containing poly(ethylene glycol) diacrylate (PEGDA) and low molecular weight polyethylene glycol (PEG) with ropinirole hydrochloride (RH) were studied as example formulations. The PEGDA to PEG (mobile phase) concentration ratio influenced drug release. It was reflected in spatiotemporal changes in parametric T2 relaxation time (T2) and amplitude (A) images obtained using magnetic resonance imaging (MRI) and T1-T2 relaxation time correlations obtained using low-field time-domain nuclear magnetic resonance (LF TD NMR) relaxometry during incubation in water. For most of the tested formulations, two signal components related to PEG and water were assessed in the hydrated matrices by MRI relaxometry (parametric T2/A images). The PEG component faded out due to outward PEG diffusion and was gradually replaced by the water component. Both components spatially and temporally changed their parameters, reflecting evolving water-polymer interactions. The study shows that dynamic phenomena related to bidirectional mass transport can be quantified in situ using NMR and MRI techniques to gain insight into drug release mechanisms from 3D printed DDS systems.

Cleaning the Electroerosive Machining Wastewater with some Polyacrylamide-Based Flocculants

The granulometric composition of the metal/scale suspensions formed at electroerosive machining (EEM) of metal items made of the ST-10 steel has been determined to evaluate the need for a flocculant for the suspension particles extraction and decontamination of the machining working fluid. Even though most suspension particles are large enough and quickly self-precipitate, some particles are too small (sized 6 µm or less) and form quite stable suspensions, requiring additional flocculants to be extracted. Pure polyacrylamide with a molecular weight of 4-5*106 atomic units and an anionic polymer flocculant BESFLOC-4041 were considered as decontamination agents for the metal/scale suspensions. It was found that the latter agent is more effective, and it ensures the effective decontamination of an EEM working fluid. An admixture of 0.05 g/L of BESFLOC-4041 ensures effective clarification (with the decontamination efficiency of 90-95 %) of the metal/scale suspension with a dispersed phase concentration of up to 1.0 g/L. The flocculation efficiency of polyacrylamimde is lower (67-85 %) and its best performance is achieved at the concentration of 0.08 g/L.

Effects of solution aging treatments on microstructure features, tensile properties and low-cycle fatigue behavior of Ti-6.2Al-4.26Mo-1.33Mn alloy

High-performance titanium alloy fasteners play an important role in the aerospace industry as important general basic parts. This work developed a high-elastic-modulus Ti-6.2Al-4.26Mo-1.33Mn alloy with good balance of strength and plasticity through regulating its primary equiaxed α (αp) phase with solution aging treatment. The influence of αp on the tensile properties and low-cycle fatigue (LCF) behavior of the alloy was investigated systematically, and the crack propagation mechanism of fatigue fracture of titanium alloy was revealed. The results show that with increasing solution temperature, the content of αp phase decreases from 43.6 % to 15.1 % in the range of 825 °C–925 °C, and the LCF life is increased by almost 2 times. However, the size of αp phase is almost unchanged with a diameter of about 2.3 μm. With the increase in solution temperature, the tensile strength of the alloy is improved, while the plasticity decreases gradually. At the solution temperature of 875 °C, the ultimate tensile strength (UTS) of the alloy is 1350 MPa, which is 18.6 % higher than the as-forged alloy, with an elongation (El) of >7 %. Moreover, the fatigue performance is also significantly improved, which is associated with the reduced αp phase that was characterized to act as crack initiations and crack propagation path.

Chitosan Nanoparticles with Potential Biomedical Applications: Effect of Concentration in the Non-Solvent Phase

Chitosan Nanoparticles with Potential Biomedical Applications: Effect of Concentration in the Non-Solvent Phase

Measurement of solubility product reveals the interplay of oligomerization and self-association for defining condensate formation.

Cellular condensates often consist of 10s to 100s of distinct interacting molecular species. Because of the complexity of these interactions, predicting the point at which they will undergo phase separation is daunting. Using experiments and computation, we therefore studied a simple model system consisting of polySH3 and polyPRM designed for pentavalent heterotypic binding. We tested whether the peak solubility product, or the product of the dilute phase concentration of each component, is a predictive parameter for the onset of phase separation. Titrating up equal total concentrations of each component showed that the maximum solubility product does approximately coincide with the threshold for phase separation in both experiments and models. However, we found that measurements of dilute phase concentration include small oligomers and monomers; therefore, a quantitative comparison of the experiments and models required inclusion of small oligomers in the model analysis. Even with the inclusion of small polyPRM and polySH3 oligomers, models did not predict experimental results. This led us to perform dynamic light scattering experiments, which revealed homotypic binding of polyPRM. Addition of this interaction to our model recapitulated the experimentally observed asymmetry. Thus, comparing experiments with simulation reveals that the solubility product can be predictive of the interactions underlying phase separation, even if small oligomers and low affinity homotypic interactions complicate the analysis.

First Evidence of the Effects of Polyethylene Terephthalate Microplastics on Ruminal Degradability and Gastro-Intestinal Digestibility of Mixed Hay.

Microplastics (MPs) raise environmental concerns. However, their effects on the ruminal-gastro-intestinal system have not yet been studied. This study aims to investigate the effects of polyethylene terephthalate (PET) MPs on the ability of the ruminal-gastro-intestinal system to degrade and digest mixed hay. Using a three-step in vitro ruminal-gastro-intestinal incubation system, PET MPs were introduced at concentrations of 0, 5, 10, and 15 g/L in ruminal and gastro-intestinal solutions. Ruminal fluid was collected from three 16-month-old Piedmontese bulls. The experiment was conducted on three mixed hays and was repeated three times, with triplicate incubations in each run. The results reveal that PET MPs reduced the degradability and digestibility of crude protein. Specifically, crude protein degradation was reduced by 9% at medium and 16% at high PET MP concentrations in the ruminal phase, while the crude protein digestibility of undegraded crude protein was reduced by 8% at the lowest PET MPs concentration in the gastro-intestinal tract. Additionally, PET MPs reduced the degradation of neutral detergent fiber at medium and high PET MP concentrations in the ruminal phase by 9% and 13%, respectively. These results highlight the risks of PET MPs contamination on ruminal-gastro-intestinal functions and underscore the urgent need to mitigate MPs contamination in the livestock sector.

One-step fabrication of Polyvinylidene fluoride membranes enriched with electroactive β-Phase for secondary battery separators via simultaneous near infrared radiation and electrospinning

This study reports a one-step fabrication method to prepare polyvinylidene fluoride (PVDF) membranes enriched with electroactive β-Phase in application for secondary battery separator using near infrared radiation (NIR) heated electrospinning techniques. The electrospun PVDF fibrous membranes with NIR heating applied were investigated by various characterizations and measurements. The results present that NIR heating during electrospinning not only increased the β phase content and mechanical strength of the PVDF membranes but also improved the electrochemical performances, suggesting its potential suitability in the battery separator applications.

Physical and mechanical properties of ceramics based on ZrN-ZrO2 obtained by spark plasma sintering method

Relevance. Increasing the service life of mining tools is an important task in the development of geology associated with the investigation of new ceramic materials for functional purposes. The ability to reduce wear and thermal and chemical effects of rocks on the working elements of mining equipment determines the vector of development of the use of super-hard, high-strength and refractory ceramics. At the same time, the task is set to increase the fracture toughness of the materials used to solve the problem of maintaining the operability of equipment under conditions of critical deformations. To accomplish this task, it is necessary to study the patterns of consolidation of ceramic materials and search for the optimal combination of consolidation parameters to achieve improved physical and mechanical properties. Aim. To develop a method for producing high-density durable ceramics based on commercially available zirconium nitride powders using spark plasma sintering under vacuum conditions, to study the phase composition and physical and mechanical properties of the resulting samples. Methods. X-ray phase analysis of the studied samples, nanoindentation, microscopic analysis. Results and conclusion. The authors have studied the physical and mechanical properties of zirconium nitride consolidated by spark plasma sintering at 2000℃, a pressure of 30–60 MPa and a holding time at a given temperature of 5–10 minutes. Qualitative and quantitative X-ray phase analysis was carried out, within which the content of the main phase of zirconium nitride and zirconium dioxide phase was determined. It was found that an increase in the pressure applied during consolidation and holding time contributes to better compaction and a decrease in the porosity of the samples from 8.52 to 2.72%. It was found that with a decrease in porosity, the elastic modulus increased in the range from 320 to 378 GPa, and the hardness from 7.3 to 10.4 GPa. At the same time, by extrapolating the data, it was established that non-porous zirconium nitride samples will have an elastic modulus of 394 GPa and a Martens hardness of 11.56 GPa. For the samples under study, critical stress intensity factors were determined. It was established that at a porosity of less than 5%, the critical stress intensity factor of zirconium nitride consolidated by spark plasma sintering has values of at least 4 MPa m1/2.

A functional analysis of a resorbable citrate-based composite tendon anchor

Rapid and efficient tendon fixation to a bone following trauma or in response to degenerative processes can be facilitated using a tendon anchoring device. Osteomimetic biomaterials, and in particular, bio-resorbable polymer composites designed to match the mineral phase content of native bone, have been shown to exhibit osteoinductive and osteoconductive properties in vivo and have been used in bone fixation for the past 2 decades. In this study, a resorbable, bioactive, and mechanically robust citrate-based composite formulated from poly(octamethylene citrate) (POC) and hydroxyapatite (HA) (POC-HA) was investigated as a potential tendon-fixation biomaterial. In vitro analysis with human Mesenchymal Stem Cells (hMSCs) indicated that POC-HA composite materials supported cell adhesion, growth, and proliferation and increased calcium deposition, alkaline phosphatase production, the expression of osteogenic specific genes, and activation of canonical pathways leading to osteoinduction and osteoconduction. Further, in vivo evaluation of a POC-HA tendon fixation device in a sheep metaphyseal model indicates the regenerative and remodeling potential of this citrate-based composite material. Together, this study presents a comprehensive in vitro and in vivo analysis of the functional response to a citrate-derived composite tendon anchor and indicates that citrate-based HA composites offer improved mechanical and osteogenic properties relative to commonly used resorbable tendon anchor devices formulated from poly(L-co-D, l-lactic acid) and tricalcium phosphate PLDLA-TCP.