Healing Zone Research Articles

Adaptive healing of stress-induced dynamic cracks in a metal-organic framework membrane using nanoparticles.

Dewatering of aqueous azeotropes is crucial and pervasive in raw chemical refineries and solvent recovery in the chemical industry but is recognized as one of the most energy-intensive processes. Pervaporation using crystalline molecular sieve membranes provides an energy-efficient solution, but stress loads stemming from thermal and mechanical risks of pervaporation are most likely to cause membrane cracks, which greatly reduces reliability of membranes in real-world applications. Here, we propose adaptive healing of stress-induced dynamic cracks (AHSDC) in the membrane in a risk-responding manner before separation by using in situ-formed nanoparticles in the same chemical environment. These nanoparticles naturally filled in fissure gaps once cracks formed in the membrane, forming adaptive healing zones. Without loss of dewatering capacity, the separation durability of the membrane after AHSDC was improved by at least two orders of magnitude. The membrane also exhibited tolerance to industrial-grade azeotropes that epitomize industrial multisource nature and complexity.

Role of green open spaces in the mental health and happiness of urban communities

Background: Mental health is the most important thing in human life, but in reality in Indonesia the level of mental health disorders is still high. People who live in urban areas are vulnerable to mental health disorders such as anxiety, stress and depression which are caused, among other things, by high work pressure and lack of recreational activities. Method: This article uses a non-experimental correlational method, collecting secondary data from various sources and journal articles without experimental manipulation. The focus is on urban communities. Findings: Difficulty accessing natural things, such as rural environments, even something "green". is one of the factors that makes urban residents easily experience depression. Depression can cause decreased energy, sleep disturbances, changes in appetite, and other physical problems, therefore fulfilling recreational needs that are cheap and easily accessible through public open spaces can be a solution to reduce people's stress levels. Conclusion: Green open space (RTH) provides an opportunity to escape from fatigue, work pressure, city crowds so that people can release their stress by immersing themselves in nature and connecting themselves with the natural environment. RTH has many positive benefits so its existence is very necessary, especially in densely populated residential areas. Novelty/Originality of this article: This study proposes a model for integrating green open space (GOS) into urban planning that considers physical aspects and therapeutic functions for mental health. This model combines evidence-based GOS design with community mental health programs, creating a 'green healing zone' that can be accessed and optimally utilized by city residents to reduce stress and improve mental well-being.

Periarticular soft tissue effect following fourth generation MIS Hallux Valgus correction: Formation of a pyramid-shaped first metatarsal osseous healing zone

Literature of fourth-generation minimally invasive surgery (MIS) on hallux valgus is scarce. In this study, extra-capsular transverse osteotomies were performed on ten cadaveric specimens. The capital fragment was shifted lateral to nearly 100% of the first metatarsal width and then fixated in contemporary fashion following MIS principles. A mixture of radio-opaque solution and methylene blue dye was injected through the second screw hole into the pyramid-shaped space created after the osteotomy shift. The injection was visualized under fluoroscopy and specimen were dissected in layered fashion to assess for containment versus extravasation. The purpose of this study is to observe and describe the preservation of the joint capsule, periosteum, and soft tissue structures adjacent to the osteotomy.

‘We have a right to flourish in our own land’: using pedagogies of healing to support Indigenous students to thrive in university classrooms

ABSTRACT This article responds to a pressing question, posed by Māori university students in Aotearoa, New Zealand: How do teachers transform universities into places where Indigenous students can thrive and heal? To address this question, we engage with pedagogies of healing, a radical critique of wellbeing within the classroom. We utilized the Māori practice of wānanga to facilitate collective reflection and action. We propose three principles for enabling Māori and Indigenous healing within classrooms: engage colonial histories, foreground Indigenous forms of knowledge, and uplift students through Indigenous research on/as healing. Within these, we offer seven teaching strategies to enact a pedagogy of healing and create classroom ‘healing zones’, strategies that challenge the individualized and depoliticized approaches to wellbeing dominant within contemporary universities.

An enhanced lattice beam element model for the numerical simulation of rate-dependent self-healing in cementitious materials

This paper describes the development of a discrete lattice model for simulating structures formed from self-healing cementitious materials. In particular, a new approach is presented for simulating time dependent mechanical healing in lattice elements. The proposed formulation is designed to simulate the transient damage and healing behaviour of structures under a range of loading conditions. In addition, multiple and overlapping damage and healing events are considered. An illustrative example demonstrates the effects of varying the healing agent curing parameters on the computed mechanical response. The model is successfully validated using published experimental data from two series of tests on structural elements with an embedded autonomic self-healing system. The meso-scale model gives detailed information on the size and disposition of cracking and healing zones throughout an analysis time history. The model also provides an accurate means of determining the volume of healing agent required to achieve healing for all locations within a structural element. The importance of the information provided by the model for the design of self-healing cementitious material elements is highlighted.

A study of the void surface healing mechanism in 316LN steel

Abstract The behavior of void surface healing in 316LN steel samples undergoing thermal plasticity deformation was investigated using the Gleeble 1500 thermomechanical simulator. The characterization of the void surface after plastic deformation was analyzed under different deformation temperatures, deformation amounts, and holding time durations. The morphology evolution and microstructure of the void surface healing zone during thermal plasticity deformation and holding time duration stage were analyzed using electron back scatter diffraction imaging. The mechanism of void surface healing under thermal plasticity deformation was investigated. It was found that the degree of void surface healing increases with the degree of deformation and the duration of the holding time. Dynamic recrystallization occurred continuously at the void surface, resulting in a plethora of crystal defects and a substantial amount of energy. These conditions were conducive to atomic diffusion and migration, thereby promoting the healing process of the void surface. Maintaining high temperature after deformation can continue to provide energy for the diffusion and migration of atoms, promotes the growth of recrystallized grains, and gradually heals the void surface.

OPTIMIZATION AND EVALUATION THE EFFECTIVENESS OF IMMEDIATE PROSTHETIC APPROACHES FOR PATIENTS AFTER TEETH EXTRACTION AND MAXILLOFACIAL SURGERY

Surgical interventions in the dentoalveolar system and maxillofacial area inevitably lead to the formation of long-term healing postoperative wounds or acquired jaw defects. An accessible method of choice for early rehabilitation is considered to be direct removable dentures, however, traditional approaches to this type of treatment can lead to postoperative inflammatory complications. At the Department of Orthopedic Dentistry and Orthodontics of Ryazan State Medical University carried out orthopedic treatment in 120 patients aged from 21 to 89 years after teeth extraction and surgical interventions in the maxillofacial area during the period from 2021 to 2023. The proposed approach to treatment was to manufacture structures of immediate dentures depending on the type of oral mucosa of the prosthetic bed using additive manufacturing technologies and the creation of elastic elements of dentures bases with dynamic control of inflammatory postoperative complications using an improved Schiller-Pisarev test. The effectiveness of the proposed approach was compared with the traditional immediate dentures. According to the results of the study, it was found that the proposed protocol for treatment and diagnosis made it possible to achieve a reduction in the area of wound healing by 50% and a decrease in the area of inflammation by 78% faster compared to the traditional method. Normalization of the microcirculatory activity of the wound healing zones was achieved in the period from 10 to 20 days of observation, with the traditional method, insufficient microcirculatory activity was noted by the 30th day of observation.

Autotransplantation of a horizontally oriented fragment of the root of a removed tooth to preserve alveolar tissues

To develop a method to contain atrophy of the alveolar bone and surrounding soft tissues in the area of many cortical teeth in the first 3 months after removal for subsequent installation of a dental implant. A description of a method for containing atrophy of the alveolar bone and surrounding soft tissues after removal of the first molar of the mandible 3 months after tooth extraction is presented. The method consists in closing the mouth of the well with a horizontally oriented fragment of the root of the removed tooth with a preserved section of the ligamentous apparatus. An X-ray assessment of bone restoration in the lumen of the well was carried out according to the Hounsfield coefficient and an assessment of the condition of soft tissues in the area of surgery 3 months after removal. For histological assessment of bone maturity, bone was taken from the implantation area 14 weeks after tooth extraction. The technique allowed to preserve the quality of soft tissues close to the original; on three-dimensional X-ray images in the lumen of the well, bone restoration sufficient for the installation of a dental implant is diagnosed, the zonal value of the Hounsfield coefficient is more than 300 units; histologically, a well-developed network of coarse-fibrous trabeculae is determined with the beginning of reconstruction into lamellar bone, regeneration of the alveolar process occurs by intramembranous ossification. The proposed technique contributes to the preservation of the qualities of the marginal gum in the healing zone after tooth extraction and the formation of sufficient bone maturity in the lumen of the well.

Optimization of postoperative protocol and diagnosis of inflammatory complications of post-extraction wounds at the stages of prosthetic rehabilitation

Was to optimize the protocol for postoperative orthopedic management and diagnosis of wound healing zones in patients after multiple teeth extractions. At the Department of Orthopedic Dentistry and Orthodontics, Ryazan State Medical University, orthopedic treatment of 30 patients was carried out after the extraction of upper teeth. Patients were divided into 3 groups depending on the used immediate prostheses: (I) traditional, (II) having a shock-absorbing polypropylene mesh in their design, (III) having a drug reservoir made of elastic plastic and a ring made of monomer-free plastic in the region of the closing borders prosthesis. To assess the effectiveness of treatment, patients on days 5, 10, 20 underwent diagnostic supravital staining of the mucous membrane using an iodine-containing solution, planimetric control, and computerized capillaroscopy. In group I by the end of the observation period a pronounced dynamics of inflammation persisted in 30% of cases, the objective signs of which amounted to 12.5±2.06 mm2 of the area of the positive indicator of supravital staining, while in group II it was 7.2±2.09, in group III - 8.3±1.41 mm2 (p≤0.05). According to the results of supravital staining and capillaroscopy at day 20, in group II morphological and objective indicators of inflammation productivity were significantly higher than in group III: the density of the vascular network in group II was 52.5±2.17, in group III - 46.3±2.4 capillary loops/µm2, staining area 7.2±2.09 and 8.3±1.41 mm2, respectively (p≤0.05). More active wound healing in patients of group II was achieved by optimizing the design of the immediate prosthesis. An accessible and objective assessment of the severity of inflammation using vital staining allows you to accurately assess the dynamics of wound healing with a blurred or unexpressed clinical picture and timely suggest the features of inflammation to correct the course of treatment.

THE ROLE OF INTERCELLULAR INTERACTIONS IN THE FORMATION OF KELOID SCARS

Pathological scarring at the present stage does not have a clear pathogenetic justification, it is characterized by unpredictability and constant growth of keloid scars, the absence of regression for many years and reasonable pathogenetic treatment. Despite the fact that there is the possibility of extirpation of excess tissue, it is almost impossible to remove keloid scars without recurrence. The paper presents phenotyping data in the structure of cellular ensembles of scars with the disclosure of signaling mechanisms of fibroblast differentiation into specialized cells that secrete collagen and the main matrix of the intercellular substance with pronounced hyalinization. It has been shown that the number of macrophages in the tissue of developing keloid scars is reduced in comparison with areas of normal reparative skin regeneration and in the structure of hypertrophic scars. Given the responsibility of macrophages for the secretion of angiogenesis factors and, accordingly, further oxygenation of the tissue healing zone, the authors point to a decrease in the number of macrophages as one of the main factors inducing keloid scarring and connective tissue metaplasia.

Options to optimize the orthopedic treatment protocol to prevent inflammatory complications at the immediate prosthetic stage in patients after multiple teeth extraction

BACKGROUND: Simultaneous multiple loss of teeth significantly increases the need for immediate orthopedic treatment in dental patients, often with the use of removable immediate dentures due to general somatic pathologies and local Dental Prostheses System features.
 AIM: The study aimed to optimize the orthopedic treatment protocol for patients after multiple teeth extractions.
 MATERIAL AND METHODS: As part of the study, the orthopedic preparation of 18 patients was conducted for further permanent prosthetics. Patients underwent tooth extraction in the upper or lower jaw amounting to the formation of included, combined, or terminal dentition defects. The following were used for patient treatment: a standard protocol for immediate prosthetics, a modified protocol, including an improved method of vital mucous membrane staining of the prosthetic bed in the surgical intervention area using standard and immediate original design prostheses. The treatment option effectiveness was evaluated based on the results of diagnostic monitoring of wound healing zones in the prosthetic bed area of immediate prostheses, including visual-palpation assessment, vital oral mucosa staining with an iodine-containing diagnostic solution to control inflammation, and a modified Doppler observation method.
 RESULTS: Study results revealed that all patients, who used standard immediate prostheses without considering the diagnostic control of inflammation areas, had objective signs of inflammation up to the 20th day of treatment with low microcirculation dynamics in the wound healing area. In 4 out of 6 patients using standard immediate prostheses, considering inflammation control, the vital staining indicators by day 20 indicated a possible trend toward chronic inflammation development in the prosthetic bed area, which was confirmed by an unstable microcirculation picture. The severity of inflammatory changes was insignificant in patients who received the original design of the immediate prosthesis, starting from the 7th day of observation and minimal by the 20th day. At this time the hemodynamics are physiologically normal.
 CONCLUSIONS: Based on the study results, the orthopedic rehabilitation protocols effectiveness, with the use of a modified design based on the immediate prosthesis and permanent diagnostic, mucous membrane staining of the prosthetic bed was established to detect inflammatory complications in the wound healing areas.

Value of 3D Printed PLGA Scaffolds for Cartilage Defects in Terms of Repair.

Objective To examine the poly (lactic-co-glycolic acid) and sodium alginate (SA) scaffolds produced by 3D printing technology, access the healing morphology of bones following PLGA/SA implantation within rat cartilage, and examine osteogenesis-related factors in rat serum to determine the efficacy of PLGA/SA scaffolds in healing animal cartilage injuries. To identify the potential of this material to repair a tissue engineering osteochondral injury. Methods Polylactic acid-glycolic acid copolymer and sodium alginate were used as raw materials to create PLGA/SA scaffolds. We observed the scaffold's macrostructure and microstructure, and the scaffold's microstructure was observed through a scanning electron microscope (SEM). The mechanical toughness of a stent was assessed using a biomechanical device. Hematoxylin-eosin staining revealed immune rejection after embedding the scaffolds under the skin of SD rats. The CCK-8 cell proliferation test kit was used to measure cell proliferation. An experimental model of cartilage injury in the knee joint was created in rats. Rats were used to establish an experimental model of cartilage damage in the knee joint. 120 female rats aged 5 weeks were chosen at random from the pool and divided into the experimental and control groups. They were all completely anesthetized with an anesthetic before having the lateral skin of the knee articular cartilage incised. Implanted PLGA/SA scaffolds were not used in the control group and only in the experiment group. Both groups of rats had their muscles and skin sutured and covered in plaster bandages. On the third, seventh, fourteenth, twenty-first, twenty-eighth, and thirty-fifth days after the procedure, the two groups of rats were divided into groups. At various stages, bone tissue, blood samples, and cartilage were examined and evaluated. Immunohistochemistry was used to identify the local bone morphogenetic protein-2 (BMP2). Results (1) PLGA/SA was successfully used to build an artificial cartilage scaffold. (2) Macroscopic and SEM observation results showed the material had increased density and numerous microvoids on the surface. (3) The result of the biomechanical test showed that the PLGA/SA scaffold had superior biomechanical characteristics. (4) The stent did not exhibit any noticeable immunological rejection, according to the results of the subcutaneous embedding experiment performed on rats. (5) The CCK-8 data demonstrated that as the cell development time rose, the number of cells gradually increased. However, there was not statistically significant difference between the growth of the cells in the scaffold extract and the control group (P > 0.05). (6) A successful rat model based on a cartilage defect of the medial knee joint has been built. (7) Observations of specimens revealed that the experimental group's bone tissue score was higher than that of the control group. (8) Using immunohistochemistry, it was found that the experimental group's BMP2 expression was higher on the 7th, 14th, and 28th days than it was in the control group (P < 0.05). Conclusion Strong mechanical and biological properties are present in stable, biodegradable PLGA/SA scaffolds that mimic cartilage. We demonstrated that the cartilage biomimetic PLGA/SA scaffold may repair cartilage and prevent negative reactions such as osteoarthritis in rat knee cartilage, making it suitable as a cartilage scaffolding material for tissue engineering. The PLGA/SA scaffold was also able to promote BMP2 expression in the bone healing zone when inserted into a knee cartilage lesion. Improved cartilage damage is the outcome of BMP2's promotion of bone formation and restriction of bone resorption in the bone healing zone.

Where There’s Smoke and the Generative Documentary

<i>Where There’s Smoke</i> and the Generative Documentary

Study on Mechanical Properties of crack Healing of low carbon Steel based on cyclic Phase Transformation Heat treatment

With the rapid development of materials, metal materials are used less and less, but at this stage, metal materials are still widely used, and iron and steel materials are the most widely used. Cracks often appear in the process of metal material processing and use, and these cracks will have a certain impact on the use of metal materials. The existence of microcracks will affect the mechanical properties of materials to some extent, but in most cases, the mechanical properties of materials will be greatly reduced, and in serious cases, metal materials will break directly in the process of use or processing. The crack healing process needed after the emergence of cracks can effectively change this situation, but so far, the research on metal crack healing is still not perfect. In this paper, taking the internal crack of low carbon steel as the object, the recovery of mechanical properties of low carbon steel by cyclic phase transformation heat treatment was studied. The results show that with the increase of the healing area, the microhardness of the area after crack healing also increases, and the tensile strength of the specimen also increases after the healing. When the healing area is similar, increasing the healing time and temperature will result in grain coarsening, resulting in the decrease of microhardness and tensile strength in the crack healing zone.

Biomechanical Effects of Deep Anterior Lamellar Keratoplasty and Penetrating Keratoplasty for Keratoconus: A Finite Element Analysis.

PurposeTo theoretically compare corneal displacement and the von Mises (VM) stress distribution of deep anterior lamellar keratoplasty (DALK) and penetrating keratoplasty (PK) for keratoconus (KC) and to evaluate the effects of residual stromal thickness (RST) and intraocular pressure (IOP) on postoperative corneal biomechanics.MethodsWe performed DALK and PK simulations using Ansys by employing anisotropic nonlinear hyperelastic corneal material properties. We analyzed corneal displacement and VM stress in DALK and PK models under IOPs of 10, 15, 20, and 25 mmHg. We established two DALK models: The ideal-type DALK ensured that postoperative central corneal thickness was constant at 560 µm and the corneal graft thickness varied with RST. The clinical-type DALK ensured that corneal grafts had the same thickness (500 µm) regardless of RST. Then we analyzed the effects of RST and IOP on postoperative corneal displacement and VM stress.ResultsCorneal displacement and VM stress were lower in the DALK than in the PK model. In the ideal-type DALK model, an increase in RST was associated with increased deformation and decreased VM stress in the healing zone, except for a RST of 0 µm. In the clinical-type DALK model, deformation and VM stress in the healing zone decreased with an increase in RST, except for a RST of 0 µm.ConclusionsDALK showed more stability than PK. For the ideal-type DALK model, an increase in RST resulted in decreased postoperative corneal biomechanics in the healing zone. For the clinical-type DALK model, corneal deformation and VM stress decreased with an increase in RST, which provides numerical evidence for the design of corneal transplantation for patients with KC.Translational RelevanceIn this computational modeling study, we first theoretically compared corneal biomechanics between DALK and PK for KC. Then, the effects of RST and IOP on postoperative corneal biomechanics were investigated. Our findings provide novel insights into the optimal design for corneal transplantation for patients with KC.

Участие жировой ткани в заживлении сквозной операционной раны стенки матки крысы

Introduction. Data about the role of components of adipose tissue in the repair of damaged uterine walls are limited, although a number of authors claim that cell-based drugs from adipose tissue have a positive effect on the repair of damaged uterine walls in laboratory rodents. Meanwhile, stem cells derived from adipose tissue are considered to be the most promising type of cells in regenerative medicine. The aim of the studywas to evaluate the adipocyte components in the uterine wall of rats in healing after a full-thickness surgi-cal incision. Materials and methods. We conducted the study on 40 female Sprague Dawley rats. The animals were sub-jected to a full-thickness longitudinal incision in the wall of the right uterine horn, with the left one serving as an intact control. We carried out morphological examinations of the uterine walls daily in 5 animals from day 1 to 7 and on day 15. The sections from paraffin blocks were stained with hematoxylin and eosin and Mallory’s trichrome staining. Immunohistochemistry detected FABP4+ adipocytes and CD68+ macrophages. The morphometric study was carried out using the Leica system (Leica, Germany). The results underwent processing in the Statistica 12 software (StatSoft). Results. We noticed the period of the most active interaction of adipose tissue with the damaged horn to last from day 3 to 15 and coincide with the macrophage activation in the healing zone. The intact left uterine horn was not involved in the interaction processes with the mesenteric adipose tissue. Starting from day 3 FABP4+ cells in the uterine wall of the operated horn formed groups, creating rounded nest-like structures. Clusters of FABP4+ cells were localized in the healing zone, near the suture material, and in the perime-trium near the mesentery attachment sites. The changes over time of the indicators of the area of cell nests depended on the localization and duration of healing. There were no FABP4+ cells in the left intact horn. Conclusion. We characterized the morphological interaction of adipose tissue with the damaged uterine wall during the first two weeks after a full-thickness surgical incision of the rat uterine horn. The results of the study indicate that adipocytes take an active part in the healing after a surgical incision of the rat uterine wall at the earliest stages. Keywords: rat uterus, hysterotomy, healing, adipocytes, macrophages

Effect of Deformation Parameters on Microstructure and Mechanical Properties of Internal Crack Healing in As‐Cast 30Cr2Ni4MoV Steel

Crack defects seriously affected the quality of heavy forgings, which needed to be eliminated by forging process. In this study, the healing process of internal crack defects was studied under different deformation parameters. The internal crack was produced by drilling the sample of 30Cr2Ni4MoV steel and then compressing the sample with different deformation. The microstructure of the crack healing zone was observed using an optical microscope. Meanwhile, the static and dynamic mechanical properties of the crack healing zone were tested by room‐temperature tensile tests and impact tests, respectively. The results showed that dynamic recrystallization (DRX) and grain growth were the main factors for internal crack healing. When the forging ratio (FR) was 1.5, the cracks at the corner of the void began to heal, which was caused by DRX. At FR 2.0, the DRX was completed and the center crack was completely healed. The tensile properties of crack healing zones were restored to more than 95% of the base material. As the FR increased to 2.2, the elongation increased slightly and the yield strength decreased slightly, which indicated that the grain growth played an important role in the plastic recovery and DRX played an important role in strength recovery. The dynamic mechanical properties of the crack healing zone gradually increased with the increase of deformation. Furthermore, the maximum value of impact toughness reached FR 2.0, and the recovery rate of impact toughness was above 96%. When the deformation continues to increase, the grains grew up after DRX, which made the impact energy decrease.

The Effects of Homogenizing and Quenching and Tempering Treatments on Crack Healing

After thermal deformation and heat treatment, it can be observed that there are small, newly formed grains in the crack healing zone, which indicates that the internal crack is fully healed. However, in our previous study, the impact properties of the internal healing zone could only be partially healed. In this study, the process of homogenizing treatment was adopted to achieve grain size homogeneity. The effects of homogenizing treatment and quenching and tempering treatment on crack healing were also systematically analyzed. With the same heat treatment method, SA508-3 samples, which were subjected to multi-pass deformation, had a higher percentage recovery than those that underwent uniaxial compression. The percentage recovery of the crack healing zone was significantly improved after the process of homogenizing treatment. The impact property of the crack healing zone could be fully restored after homogenizing treatment followed by quenching and tempering treatment. However, after several episodes of heating, the grain-boundary strength decreased, and the impact value was relatively low.

Augmentation of Tendon Graft–Bone Tunnel Interface Healing by Use of Bioactive Platelet-Rich Fibrin Scaffolds

Background: Platelet-rich fibrin (PRF) is a bioactive biomaterial wherein cytokines are enmeshed within the interconnecting fibrin network. PRF can be fabricated into a patch to augment healing of the interface between a tendon graft and bone tunnel. Hypothesis: The bioactivity of a PRF scaffold is preserved after PRF is mechanically compressed into a patch. A bioactive PRF patch could promote the incorporation of a tendon graft within the bone tunnel through the formation of a tendon-bone healing zone composed of both fibrocartilaginous tissue and new bone. Study Design: Controlled laboratory study. Methods: Bioactivity of PRF was evaluated through treatment of rabbit tenocytes with PRF-conditioned medium and cultivation of cells on a PRF patch. Cellular morphologic features, viability, and differentiation were analyzed accordingly. In an animal study, a rabbit tendon-bone healing model was established through use of New Zealand White rabbits. The implanted tendon graft was enveloped circumferentially with a bioactive PRF patch before being pulled through a bone tunnel in the proximal tibia. Micro–computed tomography (micro-CT) imaging and histological and biomechanical analyses of the tendon-bone interface were performed at 12 weeks postoperatively. Results: PRF improved the viability of the cultured tenocytes. The effects of PRF on in vitro mineralization of tenocytes were comparable with the effects of standard culture medium. The gene expressions of type I collagen and osteopontin were upregulated upon PRF treatment. For the in vivo study, micro-CT images revealed significant new bone synthesis at the tendon-bone interface in the PRF-enveloped group. The tendon-bone healing zone was characterized by abundant fibrocartilage tissue and new bone formation as demonstrated by histological analysis. Biomechanical testing showed significantly higher ultimate loads in the PRF-enveloped group. Conclusion: Bioactive PRF could effectively augment healing of tendon graft to bone by inducing the formation of a transitional tendon-bone healing zone composed of fibrocartilage and bone. Clinical Relevance: Complete healing of the tendon graft in the bone tunnel is a prerequisite for successful ligament reconstruction, which would allow early and aggressive rehabilitation and rapid return to preinjury activity level. From a translational standpoint, the PRF-augmented healing in this rabbit animal model showed a promising biological approach to enhance tendon graft to bone healing via promotion of the functional anchorage between the 2 different materials.

Effect of deformation modes and heat treatment on microstructure and impact property restoration of internal crack healing in SA 508 steel

In this study, the effects of deformation modes and quenching and tempering (Q&T) process on the crack healing and percentage recovery of impact properties were studied. The microstructure, Charpy impact properties and fracture surface morphology of the crack zones at different healing stages were evaluated. When the healing temperatures was 950 °C and 1050 °C, percentage recovery of impact properties of the internal crack healing by multi-pass thermal deformation (twice upsetting and once drawing) was lower than that by uniaxial compression. After deformed by twice upsetting and once drawing at 1150 °C, the ‘Z type’ newly formed grain belt was observed in the crack healing zone, which showed high resistance to the dynamic load. After Q&T process, the microstructure was evolved into the tempered bainite, and residual austenite decomposed gradually to carbides, precipitating out mainly along the grain boundaries. After Q&T process, the impact toughness of the crack healing zones were improved, but the percentage recovery decreased, it is because that in the crack healing zone, the carbides aggregated in the line, which has a lower resistance to applied force than the matrix.