Conversion of toxic pyrogenic products into syngas through catalytic pyrolysis of insulation material waste under the presence of CO2.

Plastic-based insulation materials have been widely employed owing to their exceptional durability, cost-effectiveness, low weight, and low thermal conductivity. Nevertheless, the disposal of the insulation material waste (IMW) within construction waste and its recycling and recovery are challenging. Meanwhile, landfilling or incineration methods can release toxic chemicals into the environment. Consequently, the accumulation of IMW in construction waste has become a pressing environmental concern. To address this issue, this paper proposes a pyrolysis platform as a disposal management method for IMW that employs CO2 as a reactive medium. IMW composed of polystyrene in the form of extruded polystyrene underwent pyrolysis to yield pyrogenic products containing toxic chemicals. These toxic chemicals were subsequently transformed into syngas via homogeneous reactions with CO2 under certain thermal conditions and Ni/Al2O3 catalyst. This resulted in a significant reduction in the total peak areas of toxic substances in the pyrogenic oil compared with that obtained using N2 as a medium. Furthermore, the efficacy of CO2 was demonstrated to increase with an increase in the atmospheric concentration. This study implied that catalytic pyrolysis under CO2 conditions is a potential platform for converting toxic chemicals from IMW into syngas through homogeneous reactions with CO2.

Functional use of carbon dioxide for the sustainable valorization of orange peel in the pyrolysis process.

Although biomass is carbon-neutral, its use as a primary feedstock faces challenges arising from inconsistent supply chains. Therefore, it becomes crucial to explore alternatives with reliable availability. This study proposes a strategic approach for the thermochemical valorization of food processing waste, which is abundantly generated at single sites within large-scale processing plants. As a model biomass waste from the food industry, orange peel waste was particularly chosen considering its substantial consumption. To impart sustainability to the pyrolysis system, CO2, a key greenhouse gas, was introduced. As such, this study highlights elucidating the functionality of CO2 as a reactive feedstock. Specifically, CO2 has the potential to react with volatile pyrolysates evolved from orange peel waste, leading to CO formation at ≥490 °C. The formation of chemical constituents, encompassing acids, ketones, furans, phenols, and aromatics, simultaneously decreased by 15.1 area% in the presence of CO2. To activate the efficacy of CO2 at the broader temperature spectrum, supplementary measures, such as an additional heating element (700 °C) and a nickel-based catalyst (Ni/Al2O3), were implemented. These configurations promote thermal cracking of the volatiles and their reaction kinetics with CO2, representing an opportunity for enhanced carbon utilization in the form of CO. Finally, the integrated process of CO2-assisted catalytic pyrolysis and water-gas shift reaction was proposed. A potential revenue when maximizing the productivity of H2 was estimated as 2.62 billion USD, equivalent to 1.11 times higher than the results from the inert (N2) environment. Therefore, utilizing CO2 in the pyrolysis system creates a promising approach for enhancing the sustainability of the thermochemical valorization platform while maximizing carbon utilization in the form of CO.

Intravesical bacillus Calmette-Guérin-induced myopathy presenting as rhabdomyolysis: a case report.

Intravesical bacillus Calmette-Guérin (BCG) instillation is an adjuvant treatment for non-muscle-invasive urinary bladder cancer. Although most complications associated with BCG immunotherapy are mild and self-limiting, rare albeit serious complications have been reported. Only a few cases of BCG-related rhabdomyolysis have been reported. In this study, we present the case of a 72-year-old woman who developed severe weakness and hyperCKemia following intravesical BCG instillation. A muscle biopsy was performed, and a diagnosis of drug-induced myopathy was made.

Effect of age on the prognosis of intrahepatic cholangiocarcinoma.

BACKGROUND/AIMS: Intrahepatic cholangiocarcinoma (iCCA) is a subgroup of cholangiocarcinoma and is the second- most-common primary hepatic tumor. Several predictive and prognostic factors have been analyzed; however, in this study we focused on the influence of age. Our aim was to use real-world results to determine the influence of age in iCCA patients. METHODS: A retrospective analysis of patients treated between 2005 and 2016 at Konkuk University Medical Center. In total, 133 patients with iCCA were identified. The mass-forming, periductal-infiltrating, and intraductal-growth types were included; patients with extrahepatic or hilar-type cholangiocarcinoma were excluded. We defined two groups: a younger group, age < 65 years, and an older group, age ≥ 65 years. Statistical analyses using univariate and multivariate Cox regression analyses, including the Kaplan-Meier method, were conducted. RESULTS: In total, 114 patients were enrolled. The two groups differed with regard to treatment options such as surgery with adjuvant chemotherapy or palliative chemotherapy (p = 0.012, p < 0.001). The younger group had significantly longer survival than the older group (p = 0.017). In the younger group, patients who received therapy had longer survival than those who did not (hazard ratio, 3.942; 95% confidence interval, 2.053 to 7.569; p < 0.001). Multivariate analysis indicated that younger age, lower bilirubin, low CA 19-9, and no lymph-node involvement were independent factors for improved survival. CONCLUSION: Younger patients and those who underwent surgery with adjuvant chemotherapy had longer survival. The younger the patient, the more treatments received, including palliative chemotherapy.

Switching from Tenofovir-Based Combination Therapy to Tenofovir Monotherapy in Multidrug-Experienced Chronic Hepatitis B Patients: a 5-Year Experience at Two Centers.

Patients with chronic hepatitis B (CHB) who were administered tenofovir disoproxil fumarate (TDF)-based combination therapy after receiving multiple drugs are frequently switched to TDF monotherapy in South Korea. We evaluated the efficacy and safety of switching to TDF monotherapy from TDF-based combination therapy over 5 years. This was a retrospective study of multidrug-experienced CHB patients who switched from TDF-based combination therapy to TDF monotherapy after achieving a virologic response (VR; <20 IU/mL) at Konkuk University Hospital and Sanggye Paik Hospital. The biochemical response was defined as a normalized serum ALT level during follow-up. Each patient was assessed from the date of switching to TDF monotherapy to the date of the last follow-up over 5 years. A total of 39 patients who received at least one antiviral therapy before TDF-based combination therapy were analyzed. The median duration of VR before switching to TDF monotherapy was 18 months and the median duration of TDF monotherapy was 55 months. In this study, except for one patient who had poor compliance, all patients maintained a VR. Three patients had a temporarily increased HBV DNA level and 91.2% of the patients showed a biochemical response. Switching multidrug-experienced patients to TDF monotherapy is generally safe and effective.

Valorizing plastic toy wastes to flammable gases through CO2-mediated pyrolysis with a Co-based catalyst.

Toys are discarded due to their short life cycle. Unfortunately, development of sustainable disposal platform for toy has not gained particular concern. To establish a reliable disposal platform, this study employed a pyrolysis platform to valorize plastics into value-added fuels. To confer more environmentally resilient process, CO2 was used as a feedstock to enhance the process efficiency from a perspective of the yield of flammable gases. To this end, waste toy brick (WTB) was used as a model compound. The exact types of plastics (polyacrylonitrile, polybutadiene, polystyrene, and polymethyl methacrylate) in WTB were experimentally determined. In pyrolysis of WTB, the complicated mixture of benzene derivatives was inevitably generated. To detoxify them by means of syngas (H2/CO) production, catalytic pyrolysis was performed. Co catalyst effectively induced chemical bond scissions, leading to substantially enhanced H2 formation. Also, the gas phase reactions (GPRs) between CO2 and volatile compounds over Co catalyst expedited the production rate of CO, and such CO enhancement effectively offered a chance to mitigate toxic chemical generations. The synergistic contribution of CO2 and Co catalyst enhanced syngas formation more than 25 times in reference to pyrolysis of WTB without Co catalyst. The GPRs also greatly prevented catalyst deactivation.

Post-processing calcium subtraction method to minimize stenosis-overestimation by blooming artifact.

BACKGROUND: CT images are often affected by blooming artifacts during the diagnosis that facilitate an overestimation of the expression of calcification stenosis, thereby impeding the accurate diagnosis of this condition. OBJECTIVE: Arterial calcification can act as a blooming artifact in computed tomography (CT) images, leading to overestimations of the blood vessel and the size of calcified plaque. This study proposes an improved CT post-processing method that accurately measures calcium and lumen size in blood vessels. METHODS: Six hundred and thirty calcium datasets were obtained from 63 patients diagnosed with a vascular disease. Patients were grouped into three sets corresponding to each image acquisition method used: G1, for the invasive coronary angiography (ICA); G2, for multiplanar reconstruction (MPR) imaging and post-processing; and G3, for the novel method of mixed Gaussian filter and K-mean clustering (GK). Results of GK were generated by adding Gaussian and k-mean clustering algorithms to the MPR post-processing procedure. The analysis of variance (ANOVA), linear regression, and intraclass correlation coefficient (ICC) were used to compare the accuracy and sensitivity of the different methods. All measurements were performed multiple times to mitigate human error. RESULTS: The ANOVA test revealed no significant differences between the G1 and G3 groups. Hence, linear regression was used to analyze the correlation between the G1 and G3 groups (p< 0.05, R2 = 0.885), and a higher correlation than G1 and G2 was reported (p> 0.05, R2 = 0.432). ICC was performed for reproducibility, wherein high correlation was identified among all groups. CONCLUSIONS: Results of the study indicate that the GK method yields images that are very similar to ICA image measurements. This suggests that the GK can be used as a more effective post-processing method over the inaccurate MPR while remaining non-intrusive when determining the arterial stenosis degree, unlike the ICA.

Valorization of carbon dioxide and waste (Derived from the site of Eutrophication) into syngas using a catalytic thermo-chemical platform.

Global warming increases a chance of eutrophication, and such fact offers that unhygienic organic waste materials (OWMs) in water must be treated. Hence, this study laid emphasis on the thermal-chemical (pyrolysis) process to establish a rapid valorization platform for OWMs. Indeed, OWMs were collected from the eutrophication site, and OWMs were mainly comprised of lignocellulosic biomass, microalgae (cyanobacteria) and the diverse types of bacteria (commonly observed from livestock waste). In an attempt to offer more sustainable valorization route for OWMs, CO2 was used as a raw material in pyrolysis process. From the CO2-assisted pyrolysis, the conversion of CO2 and OWMs into gaseous fuel (CO) was observed. A cheap Ni-based catalyst was used in pyrolysis of OWMs as a strategic practice to promote conversion of CO2 into CO. Indeed, syngas production (38 %) was enhanced from catalytic pyrolysis over Ni/SiO2 under CO2 condition as compared to inert condition (N2).

3D print material study to reproduce the function of pig heart tissue.

BACKGROUND: Three-dimensional (3D) printing technology for heart simulation can be represented as complex anatomical structures, and objective information can be provided. OBJECTIVE: We studied 3D print material to find a material with the same elastic coefficient as pig elastic coefficient. METHODS: Pig heart sample, Agilus sample, Tango sample, TPU sample, and silicone sample were studied. The elastic coefficient of each specimen was measured using an elastic coefficient measuring instrument. The analysis was performed using the average value of ten specimens of the same size. We suggested an equation to find the elastic coefficient of material by the thickness using the elastic coefficient of Agilus, Tango, and silicone. RESULTS: The sample with similar elasticity to the pig sample did not show the same coefficient of elasticity at the same sample size. In Tango, the 0.5 mm high elastic force was about 3 times higher than the pig sample 7 mm elastic force. CONCLUSIONS: The study was conducted using 3D print material and silicone which can reproduce the elasticity of pig heart. However, no material is currently available to reproduce pig heart sample of the same size. However, if the heart is developed considering only elasticity, it can be sufficiently reproduced using the research results.

Enhancement of sophorolipids production in Candida batistae, an unexplored sophorolipids producer, by fed-batch fermentation.

Sophorolipids (SLs) from Candida batistae has a unique structure that contains ω-hydroxy fatty acids, which can be used as a building block in the polymer and fragrance industries. To improve the production of this industrially important SLs, we optimized the culture medium of C. batistae for the first time. Using an optimized culture medium composed of 50 g/L glucose, 50 g/L rapeseed oil, 5 g/L ammonium nitrate and 5 g/L yeast extract, SLs were produced at a concentration of 24.1 g/L in a flask culture. Sophorolipids production increased by about 19% (28.6 g/L) in a fed-batch fermentation using a 5 L fermentor. Sophorolipids production more increased by about 121% (53.2 g/L), compared with that in a flask culture, in a fed-batch fermentation using a 50 L fermentor, which was about 787% higher than that of the previously reported SLs production (6 g/L). These results indicate that a significant increase in C. batistae-derived SLs production can be achieved by optimization of the culture medium composition and fed-batch fermentation. Finally, we successfully separated and purified the SLs from the culture medium. The improved production of SLs from C. batistae in this study will help facilitate the successful development of applications for the SLs.

Comparative study on carbon dioxide-cofed catalytic pyrolysis of grass and woody biomass.

This study investigated the mechanistic functions of CO2 on the pyrolysis of two different biomasses to elucidate the effect of CO2 on syngas formations during pyrolysis. To this end, CO2-assisted pyrolysis of cellulosic biomass (barnyard grass, Echinochloa) and lignin-rich woody biomass (retinispora, Chamaecyparis obtusa) were compared. The confirmed mechanistic effectiveness of CO2 on pyrolysis of biomass was gas phase reactions between CO2 and volatile matters from biomass pyrolysis. Lignin-rich biomass had more CO2 susceptibility, resulting in more enhanced CO formation via the gas phase reactions. To expedite the slow reaction rate of the gas phase reactions during biomass pyrolysis, earth-abundant catalysts (Co/SiO2 and Ni/SiO2) were employed for pyrolysis of two biomass substrates. With Co and Ni catalysts, the syngas formations were 2 and 3 times higher comparing to the pyrolysis of without catalyst. The cumulative formations of syngas from lignin-rich biomass was nearly doubled than that from cellulosic biomass.

Ultrasonographic evaluation of chronic shoulder pain after breast cancer surgery: single center, cross-sectional study.

Chronic shoulder pain is a common complication in breast cancer patients after surgery. Chronic shoulder pain after breast cancer surgery was formerly considered as neuropathic pain, however the pathophysiology including structural damages has not been assessed comprehensively. We hypothesized that the structural change could be one of the cause of shoulder pain after breast cancer surgery and evaluated various ultrasonography findings of the shoulder in breast cancer patients with chronic shoulder pain. Patients who were suffering from chronic shoulder pain on unilateral side for at least 3 months after breast cancer surgery were enrolled from a single tertiary hospital. Demographic and clinical data were collected at the baseline. Articular and adjacent structures of both shoulders (painful and contralateral side) were evaluated by ultrasonography. The ultrasonography findings were compared between painful and contralateral sides. Logistic regression analysis was performed to determine the factors associated with abnormal ultrasonography findings. Fifty-two female patients (average age of 55) were enrolled. Significantly more abnormal ultrasonography findings were observed in the painful side than in the contralateral side [39 (75.0%) vs 11 (21.2%), P < 0.001]. The coracohumeral ligament was significantly thicker in the painful side than in the contralateral side (2.48 ± 0.69 vs 1.54 ± 1.25 mm, P < 0.001); adhesive capsulitis was also more frequent in the painful side [14 (26.9%) vs 0, P < 0.001]. Furthermore, patients with a history of breast cancer surgery on the ipsilateral side were associated with abnormal ultrasonography findings and adhesive capsulitis. This study is the first to evaluate ultrasonography in patients with chronic shoulder pain after breast cancer surgery. The results showed that ultrasonography could reveal several structural problems in these patients.

Sequential growth factor releasing double cryogel system for enhanced bone regeneration.

Bone regeneration is a complicated physiological process regulated by several growth factors. In particular, vascular endothelial growth factor (VEGF) and bone morphogenetic protein-4 (BMP-4) are regarded as key factors that induce bone regeneration by angiogenesis and osteogenesis. In this study, we developed a double cryogel system (DC) composed of gelatin/chitosan cryogel (GC) surrounded by gelatin/heparin cryogel (GH) for dual drug delivery with different release kinetics. VEGF was loaded in GH (outer layer of DC) for the initial release of VEGF to induce angiogenesis and provide blood supply in the defect area, while BMP-4 was loaded in GC (inner layer of DC) that leads to sustained release for continuous osteogenic induction. After analyzing characteristics of the double cryogel system such as porosity, degradation rate, swelling ratio, and mechanical properties, we evaluated release kinetics of VEGF (initial release) and BMP-4 (sustained-release) by ELISA. Then, the timely release of VEGF and BMP from DC synergistically induced in vitro osteogenic differentiation as confirmed by alkaline phosphatase staining, Alizarin Red S staining, and real-time PCR analysis. Finally, a critical-sized cranial defect model confirmed the enhanced bone regeneration as a result of dual release growth factor mechanisms.

Metabolic Syndrome and the Risk of Thyroid Cancer: A Nationwide Population-Based Cohort Study.

Background: The association of metabolic syndrome and its components with the risk of thyroid cancer is unclear. Thus, we conducted a large-scale, nationwide, population-based, cohort study to investigate this relationship. Methods: We studied 9,890,917 adults without thyroid cancer from the Korean National Health Insurance health checkup database from January 1 to December 31, 2009. Individuals with at least three of the following five components were diagnosed with metabolic syndrome: abdominal obesity, hypertriglyceridemia, low high-density lipoprotein-cholesterol levels, elevated blood pressure, and hyperglycemia. Multivariate Cox proportional hazards models were used to estimate thyroid cancer risk. Results: During the average 7.2 years of follow-up, 77,133 thyroid cancer cases were newly identified. The thyroid cancer risk was higher in the metabolic syndrome group than in the nonmetabolic syndrome group (hazard ratio [HR] 1.15 [95% confidence interval, CI 1.13-1.17]). The association between metabolic syndrome and thyroid cancer risk was significant in the obese group (HR 1.10 [CI 1.07-1.13]) and not in the nonobese group (HR 1.002 [CI 0.98-1.03]). The effect of metabolic syndrome on the risk of thyroid cancer differs according to obesity (p for interaction = 0.017). People with all five components of metabolic syndrome had a 39% higher risk than those without any components (HR 1.39 [CI 1.33-1.44]). The higher risk of thyroid cancer in people with all five components was significant in the obese group (HR 1.29 [CI 1.21-1.38]), but not in the nonobese group (HR 1.06 [CI 0.98-1.14]). There was a significant interaction between the number of metabolic syndrome components and obesity (p for interaction <0.0001). For the combined effect of obesity and metabolic syndrome on the risk of thyroid cancer, obese men with metabolic syndrome had the highest risk of thyroid cancer compared with those without (HR 1.58 [CI 1.52-1.64]), but obese women with metabolic syndrome did not. Conclusions: Metabolic syndrome was associated with an increased risk of thyroid cancer in the Korean general population. Metabolic syndrome had a more significant risk of thyroid cancer in the obese group. Metabolic syndrome and obesity were associated with a higher risk of thyroid cancer in men but not in women.

CO2-cofed catalytic pyrolysis of tea waste over Ni/SiO2 for the enhanced formation of syngas.

To valorize tea waste (TW), catalytic pyrolysis was done as a practical measure for recovering energy as a form of syngas. Considering CO2 as a reactive gas medium in place of conventional pyrolysis gas, a sustainable pyrolysis platform was established. In addition, mechanistic effectiveness of CO2 on TW pyrolysis was examined. In the presence of CO2, homogeneous reaction with volatile organic compounds (VOCs) derived from TW pyrolysis contributed to CO formation. To enhance the formation of syngas at low pyrolysis temperature, catalytic pyrolysis over a Ni/SiO2 was investigated. The synergistic effects of Ni/SiO2 catalyst and CO2 promoted thermal cracking of VOCs and further homogeneous reaction with CO2, thereby resulting in the substantial enhancement (28 times more) of H2 and CO production than non-catalytic pyrolysis. It was also confirmed that CO2 could be considered a reactive gas medium to produce biochar (34-35 wt.% yield), having competitive porosity and surface area, in comparison to that from pyrolysis in N2. Therefore, CO2 can be employed to build a sustainable waste conversion platform for energy and biochar production through pyrolysis instead of using N2.

3-D Space Visualization System Using Ultrasonic Sensors as an Assistive Device for the Blind.

This study proposes a new assistive device for the blind that uses more than one-dimensional data to draw objects. The study aims to convert three-dimensional (3-D) spatial information into sound information using 6-axis and ultrasonic sensors, and to draw a 3-D depiction of the space ahead for the user. Fourteen participants were involved in testing, wherein 4 were visually impaired. Moreover, the male to female ratio was 7:3, with the average age of participants at 28.8 years. An initial sound recognition experiment was designed to assess the device's accuracy through participant use. Recognition rates were 70% for normal participants and 88% for the blind participants. Additional experiments expanded the environmental conditions by requiring participants to discern the distances of 10 objects, positioned at both high and low locations. Two different scenarios were employed: stationary and walking scenarios. The stationary distance measurement participants scored an average of 96 points, while the walking participants averaged 81 points. Under the given conditions, this study found that its assistive device for the visually impaired can draw a 3-D space with 88.5% accuracy. This probability promises a basic level of utility that can assist those with visual impairment in controlled environments, such as hospitals and homes.

Analysis of Correlation Between Contrast and Component of Polylatic Acid Composite for Fused Deposition Modeling 3D Printing.

Additive manufacturing or three-dimensional (3D) printing is considered a disruptive technology for producing components with topologically optimized complex geometries as well as functionalities that are not achievable by traditional methods. 3D printing is expected to revolutionize the manufacturing of components. While several 3D printing systems are available, printing based on fused-deposition modeling (FDM) using thermoplastics is particularly widespread because of the simplicity and potential applicability of the method. In this study, we report the analysis of correlation between contrast and component of polylactic acid (PLA) based composite for FDM 3D printing. The pre-fabricated white composite and black composite were mixed in the fraction of 100:0, 90:10, 75:25, 50:50, 25:75, and 0:100% (v/v) and the obtained mixture was extruded using HX-35 3D filament extrusion line. The samples in different contrast were printed in disk like shape, and the gray scale filaments and 3D printed samples were measured the morphology and components using a field emission scanning electron microscope and energy dispersive X-ray spectroscopy. The CIE-lab values of the samples were measured using a colorimeter and the correlation between CIE-lab values and the components were analyzed. Although the component of Ti was linearly increased, the CIE-lab values show a clear exponential increase by increasing the white composite.

High-level production and high-yield recovery of lactobionic acid by the control of pH and temperature in fermentation of Pseudomonas taetrolens.

Lactobionic acid (LBA) was produced by fermentation of Pseudomonas taetrolens. First, to increase the production of LBA by P. taetrolens, we controlled the pH of culture medium by CaCO3 addition (30 g/L) and then examined the initial lactose concentration ranging from 50 to 200 g/L and the growth temperature ranging from 20 to 37 °C. Both the LBA production titer (180 g/L) and the productivity (2.5 g/L h) were highest at 200 g/L lactose concentration and 25 °C of cell growth temperature in shake-flask culture. Although the production of LBA (178 g/L) was almost similar during the batch fermentation of P. taetrolens using 5 L bioreactor, the LBA productivity highly increased to 4.9 g/L h. The method using ethanol precipitation and ion-exchange chromatography was developed to recover the pure LBA from the fermentation broth. The optimum volume of ethanol and pH of culture medium for the precipitation of Ca2+ salt form of LBA were six volume of ethanol and pH 6.5, respectively. The cation-exchange resin T42 finally showed the best recovery yield (97.6%) of LBA from the culture supernatant. The production titer (178 g/L) and the productivity (4.9 g/L h) of lactobionic acid in this study were highest among the previous studies ever reported using P. taetrolens as a production strain of LBA.

Development of a visual information to auditory information transformation system for ambulation assistance.

BACKGROUND: Assistant equipment for the visually impaired has a white cane. If the information in the three-dimensional space is transmitted by sound, the blind can draw a three-dimensional space. OBJECTIVE: This study developed "Visual System," an ambulation aid/guide for the blind that transforms visual-spatial information into auditory information, and verified its utility. Unlike conventional systems, which are in essence simple collision-warning systems, Visual System helps the visually impaired to recreate their surroundings and to be cognizant of the location and proximity of obstacles. METHODS: Ten subjects with normal vision (mean age: 32.4 years; male-to-female ratio: 6 to 4) were selected for blind tests. The subjects were instructed to detect and avoid obstacles presented in various three-dimensional settings. Prior to the tests, experiments were conducted to determine the distance to each subject. Upon completion of Visual System-based detection training, obstacles were presented and tests conducted. For evaluation, the subjects' vertical position detection, horizontal position detection, distance detection, and overall performance success were each evaluated. RESULTS: The total performance scores ranged between 88 (lowest) and 100 (highest), with a mean score of 91.5. CONCLUSIONS: The results indicate that Visual System as a product can assist the visually impaired in their daily functioning.

Bioactive calcium phosphate materials and applications in bone regeneration.

BACKGROUND: Bone regeneration involves various complex biological processes. Many experiments have been performed using biomaterials in vivo and in vitro to promote and understand bone regeneration. Among the many biomaterials, calcium phosphates which exist in the natural bone have been conducted a number of studies because of its bone regenerative property. It can be directly contributed to bone regeneration process or assist in the use of other biomaterials. Therefore, it is widely used in many applications and has been continuously studied. MAINBODY: Calcium phosphate has been widely used in bone regeneration applications because it shows osteoconductive and in some cases osteoinductive features. The release of calcium and phosphorus ions regulates the activation of osteoblasts and osteoclasts to facilitate bone regeneration. The control of surface properties and porosity of calcium phosphate affects cell/protein adhesion and growth and regulates bone mineral formation. Properties affecting bioactivity vary depending on the types of calcium phosphates such as HAP, TCP and can be utilized in various applications because of differences in ion release, solubility, stability, and mechanical strength. In order to make use of these properties, different calcium phosphates have been used together or mixed with other materials to complement their disadvantages and to highlight their advantages. Calcium phosphate has been utilized to improve bone regeneration in ways such as increasing osteoconductivity for bone ingrowth, enhancing osteoinductivity for bone mineralization with ion release control, and encapsulating drugs or growth factors. CONCLUSION: Calcium phosphate has been used for bone regeneration in various forms such as coating, cement and scaffold based on its unique bioactive properties and bone regeneration effectiveness. Additionally, several studies have been actively carried out to improve the efficacy of calcium phosphate in combination with various healing agents. By summarizing the properties of calcium phosphate and its research direction, we hope that calcium phosphate can contribute to the clinical treatment approach for bone defect and disease.