HA Sample Research Articles

Who will stay a little longer? Predicting length of stay in hip and knee arthroplasty patients using machine learning

BackgroundHospital length of stay (LoS) varies widely across hip (HA) and knee arthroplasty (KA) patients and depends on multiple factors. Prediction methods are necessary to improve hospital capacity planning and identify patients at risk of long LoS. This study aims (1) to compare the performance of previously applied machine learning (ML) as well as regression methods for either LoS classification or regression in a multi-hospital setting for primary HA and KA patients. In addition, the study aims (2a) to assess which variables are the most important predictors for LoS prediction and, specifically, (2b) whether patient-reported outcome measures (PROMs) collected before surgery act as important predictors. Methods2611 primary HA and 2077 primary KA patients from eight German hospitals were included to train and test extreme gradient boosting (XGBoost), naïve Bayes (NB) and logistic regression (LogReg) for classification, and XGBoost as well as a linear regression (LinReg) for regression. Area under the receiver operating characteristics curve (AUC) and mean absolute error (MAE) were used as primary performance indicators for classification and regression. ResultsFor classification, the highest AUC was reached by XGBoost and LogReg (AUC = 0.81) in the HA sample, whereas NB was statistically significantly outperformed by both other methods. In the KA sample, no statistical difference between any method was found, and AUC was lower for all models compared with HA. For regression, MAE was lowest for XGBoost (1.43 days for HA and 1.21 days for KA). PROMs and hospital indicators were among the most relevant predictors in all cases. ConclusionThe study demonstrated robust performance of ML in predicting LoS. PROMs reflect relevant features for prediction. They should be routinely collected and used for practical applications. XGBoost may act as a superior prediction tool compared to regression or other ML models in certain circumstances.

Enhanced strength-ductility synergy in a selective laser melted Inconel 718 superalloy by refining γ″ precipitates

An optimized heat treatment procedure containing homogenization and single aging at temperature of 700°C (HA700) was proposed for selective laser melted Inconel 718 superalloy. The results showed that many ultrafine γ′ and γ″ phases with size of 10–35 nm precipitated from the HA700 sample due to reduced aging temperature and time. Especially, the morphology of γ″ phase changed to be near spherical shape with aspect ratio of 1–3 rather than typical disc-like shape in the traditional homogenized plus double aged sample (HA). With the aid of well-dispersed ultrafine γ″ precipitates, the HA700 sample achieved a simultaneous improvement in strength of ∼10% and ductility of ∼13% compared to HA sample. This single aging strategy could provide new insights into optimizing the mechanical properties of Inconel 718 alloy.

Surface and micromechanical analysis of polyurethane plates with hydroxyapatite for bone structure

To analyze the surface topography and mechanical properties of a polyurethane derived from castor oil reinforced with hydroxyapatite (PU–HA) for bone fixation. The surface analysis was performed by Scanning Electron Microscopy (SEM) and the mechanical properties by Vickers microhardness and tensile tests. The SEM images showed that the PU surface presented important characteristics for materials intended for bone fixation, such as an irregular and porous surface. The analysis showed a surface with alternating areas with depressions and elevations of approximately 80±100 µm, presence of pores of 12 µm in size. The microhardness analysis showed values of 0.42±1.01 HV for PU–HA plates, lower in relation to the poly lactic-co-glycolic acid (PLGA) plate (control group). The elastic modulus and ultimate tensile strength of 317.4 MPa, and 35.57 MPa for PLGA sample, 1.187 MPa, and 0.29 MPa for PU–HA sample. The PU produced showed good surface properties, however demands better mechanical properties.

Aqueous humour concentrations after topical apPlication of combinEd levofloxacin-dexamethasone eye dRops and of its single components: a randoMised, assEssor-blinded, parallel-group study in patients undergoing cataract surgery: the iPERME study

PurposeTo evaluate the penetration of levofloxacin and dexamethasone sodium phosphate into the aqueous humour (AH) after administration in combination and as single molecules. Evaluation of the penetration of those agents in the site of action and their pharmacodynamic potential activity in view of the intended clinical use after cataract surgery.MethodsRandomised, assessor-blinded, parallel-group. Patients scheduled for cataract surgery were assigned in a 1:1:1 ratio to: levofloxacin + dexamethasone sodium phosphate (L-DSP), Levofloxacin (L) or Dexamethasone sodium phosphate (DSP) eye drops. Either test or reference drugs were instilled in the cul-de-sac twice, 90 and 60 min before paracentesis.ResultsA total of 125 patients completed the study. Fraction of dose absorbed in the anterior chamber was 3.8–4.2 · 10−4 for levofloxacin and 0.3–0.4 · 10−4 for dexamethasone, respectively. No notable differences in concentration of levofloxacin were found between L-DSP arm (1.970 nmol/ml) and L arm (2.151 nmol/ml). The concentrations of levofloxacin were well above the MICs for the most frequent Gram-positive and Gram-negative eye pathogens. Dexamethasone concentrations were slightly lower in L-DSP arm (0.030 nmol/ml) than in DSP arm (0.042 nmol/ml), but still in the pharmacodynamically active range in the site of action. The difference was not clinically relevant. DSP was not detected in any HA sample, suggesting its full hydrolysis to free dexamethasone.ConclusionOur results confirm that no interaction is evident on the corneal penetration of levofloxacin and dexamethasone which reach pharmacologically active concentrations when instilled as fixed combination eye drops to patients undergoing cataract surgery.Trial registrationClinicalTrials.gov Identifier: NCT03740659

Efficient photocatalytic degradation of malachite green dye using facilely synthesized hematite nanoparticles from Egyptian insecticide cans.

In the present study, a combustion method was applied for the production of hematite nanoparticles from Egyptian iron waste using l-arginine (The sample was named HA) and glutamine (The sample was named HG) as organic fuels, respectively. XRD confirmed that the HA and HG products have crystallite sizes of 48 and 56 nm, respectively. Also, HR-TEM demonstrated that spherical and irregular shapes have an average diameter of 45 and 59 nm were observed in the HA and HG samples, respectively. Besides, FE-SEM elucidated that spherical and irregular shapes have an average size of 142 and 196 nm were observed in the HA and HG samples, respectively. In addition, FT-IR confirmed that the peaks which were detected at 518 and 430 cm-1 are because of vibrations of Fe-O bond. Moreover, the value of the energy gap for the HA and HG samples was 1.00 and 1.45eV, respectively. Furthermore, the PL emission spectra elucidated that the emission intensity of the HA sample was less than that of the HG sample. So, e-/h+recombination rate of the HA sample was less than that of the HG sample. Hence, the photocatalytic degradation of malachite green dye using the HA sample was larger than that using the HG sample. In the absence of H2O2, the % degradation of malachite green dye under the influence of UV using HA and HG samples was 46.29 and 39.72 % after 3 h, respectively. Also, in the presence of H2O2, the % degradation of malachite green dye under the influence of UV using HA and HG samples was 100 % after 60 and 70 min, respectively.

Study on the microstructure and creep behavior of Inconel 718 superalloy fabricated by selective laser melting

Horizontal-direction Inconel 718 alloy cylindrical rods were fabricated by selective laser melting (SLM) and subsequently subjected to solution or homogenization plus double aging (SA or HA) treatments. Lever arm creep tests were performed with the creep tensile axis perpendicular to the building direction of the samples with a constant stress of 650 MPa at 650 °C. Scanning and transmission microscopy and electron backscatter diffraction were used to clarify the microstructure of the SA and HA samples before and after creep. The experimental results revealed that the average grain sizes of the SA and HA samples were basically the same before creep, and larger γ′ and γ″ strengthening phases existed in the HA sample. The grains tended to grow, and the higher dislocation density within grains and lower local misorientation values close to the grain boundaries occurred in the HA sample during creep, which contributed to the longer creep rupture life in comparison with the SA sample. The fracture surfaces of the SA and HA samples displayed intergranular features, and the creep voids and micro-cracks were formed around the δ or Laves phases at the grain boundaries. The creep fracture mechanism was also discussed.

Cytocompatibility and Dielectric Properties of Sr2+ Substituted Nano-Hydroxyapatite for Triggered Drug Release

Hydroxyapatite (Ca5(PO4)3OH) is a well-known bioceramics material used in medical applications because of its ability to form direct chemical bonds with living tissues. In this context, we investigate the biocompatibility and dielectric properties of Sr2+-substituted hydroxyapatite nanoparticles were synthesized by sol-gel method. The influence of strontium on the crystal structure, functional group, morphological, electrical properties, and biocompatibility of as-synthesized nano-hydroxyapatite samples was analyzed using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and field emission scanning electron microscopy (FE-SEM). Dielectrical properties of the bioactive Sr-HA sample were investigated by a dielectric impedance spectroscopy method. The observed results illustrate the incorporation of Sr2+ ions in the apatite lattice could influence the pure HA properties, by reducing the crystallite size and crystallinity quite consistent with the morphology variation. The ac conductivity (σac) increased with an increasing applied frequency confirmed that prepared HA sample exhibited the universal power law nature. Further, the in vitro drug loading and release studies using doxycycline as a model drug demonstrate that the Sr2+ -HA nanoparticles show high drug adsorption capacity and sustained drug release. Thus, the improved bioceramics system could be a promising candidate for future biomedical applications.

Enhanced Surface Properties of Hydroxyapatite by Grafting Tartaric Acid for Sustained Release of Moxifloxacin

AbstractGrafting of material with organic functionalities helps to tune material's surface properties. Surface properties of a biomaterial play a significant role for sustained release of therapeutic agent. To evaluate the effect of tartaric acid concentration on HA surface properties and phase purity, a series of tartaric acid grafted HA (t‐HA) samples were prepared via in situ wet chemical synthesis. Grafting of HA with tartaric acid improved its surface properties. The surface area of 737 m2/g was gained when 0.05 mole equivalent of tartaric acid was used for HA grafting. X‐ray diffraction patterns of t‐HA samples have shown low degree of crystallinity compared to HA sample. XRD results showed the formation of calcium tartrate phase along with HA when higher concentration of tartaric acid was used for synthesis. The HA and t‐HA samples were explored for the delivery of moxifloxacin. High surface area, surface charge and low degree of crystallinity have improved electrostatic interaction between the drug and t2‐HA and help in sustained release of moxifloxacin. In vitro antibacterial activity of drug loaded samples showed activity against S. aureus. Calcium tartrate containing samples t3‐HA, t4‐HA and t5‐HA showed, however, moderate inhibition against S. aureus without drug. In vitro cell studies by using MC3T3 cell line showed that prepared HA and t‐HA samples did not exhibit any cytotoxic effect.

Optimization of hyaluronic acid production and its cytotoxicity and degradability characteristics

In the present study, culture conditions of Streptococcus equi was optimized through Box–Behnken experimental design for hyaluronic acid production. About 0.87 gL−1 of hyaluronic acid was produced under the determined conditions and optimal conditions were found as 38.42 °C, 24 hr and 250 rpm. The validity and practicability of this statistical optimization strategy were confirmed relation between predicted and experimental values. The hyaluronic acid obtained under optimal conditions was characterized. The effects of different conditions such as ultraviolet light, temperature and enzymatic degradation on hyaluronic acid produced under optimal conditions were determined. 118 °C for 32 min of autoclaved HA sample included 63.09 µg mL−1 of d-glucuronic acid, which is about two-fold of enzymatic effect. Cytotoxicity of hyaluronic acid on human dermal cells (HUVEC, HaCaT), L929 and THP-1 cells was studied. In vitro effect on pro or anti-inflammatory cytokine release of THP-1 cells was determined. Although it varies depending on the concentration, cytotoxicity of hyaluronic acid is between 5 and 30%. However, it varies depending on the concentration of hyaluronic acid, TNF-α release was not much increased compared to control study. Consequently, purification procedure is necessary to develop and it is worth developing the bacterial hyaluronic acid.

The study of electrodeposition of hydroxyapatite-ZrO2-TiO2 nanocomposite coatings on 316 stainless steel

In this research pure HA and HA-ZrO2-TiO2 nanocomposite coatings (named HZT coatings) were successfully synthesized by merging two usual electroplating methods. In order to deposit pure HA coating a particular saline solution of Calcium and Phosphate was prepared with pH = 4.2, thermodynamically rich of hydroxyapatite. XRD and FTIR studies prove the synthesis of hydroxyapatite during electrodeposition process. To synthesize composite coatings with rational molar ratios of composite agents to matrix, two different concentrations of ZrO2-TiO2 suspensions were added to Ca-P solution at the pH = 4.2 and electrodeposition process done similar to pure HA sample. XRD, FTIR and FESEM (EDS) analyses prove that composite coatings electrodeposited successfully too. The effect of ZrO2-TiO2 composite agents on the characteristics of the coatings were investigated using X-ray diffraction (XRD), Fourier transform infrared spectra (FTIR), Field emission scanning electron microscopy (FESEM) and energy dispersive spectroscopy. Polarization test was carried out to evaluate corrosion behavior of the coatings. In-vitro test was done in SBF solution and bioactivity of coatings was evaluated using FESEM observation.Adding ZrO2-TiO2 nanoparticles makes different changes in the coating specifications. In composite coatings hydroxyapatite has higher crystallinity (92%) rather than pure HA (80%). FESEM observations reveal new morphologies of electrodeposited HA, such as micro-nanorods of HA formed in composite coatings that are not mentioned before in the literature. EDS results show that adding more nanoparticles to the solution results in more nanoparticles deposition in composite coating.The minimum corrosion current density (icorr.) of coatings was for HZT2 composite coating equal to 0.01 μA/cm2 while icorr. of bare substrate was 1.5 μA/cm2 (it means that icorr. of composite coating is 0.007 icorr. of bare substrate.). As a result of nanoparticles addition, porosity is decreased from 46% for HA coating to 6% for HZT2 coating. EIS results show that corrosion resistance of coating increased as a result of adding nanoparticles and HZT2 coating has largest charge transfer resistance among the prepared coatings.The FE-SEM observations suggest that the coatings would demonstrate bioactive behavior because natural hydroxyapatite (deposits formed during immersion) is formed during immersion.

A comparative study on the removal of Pb(II), Zn(II), Cd(II) and As(V) by natural, acid activated and calcinated halloysite

A comparative study on the removal of Pb(II), Zn(II), Cd(II) and As(V) by natural, acid activated and calcinated halloysite

The effect of pH and the process of direct or inverse synthesis of silicon-Substituted hydroxyapatite prepared by hydrolysis in aqueous medium

Nanosized hydroxyapatite with silicon substitution Ca10(PO4)6−x(SiO4)x(OH)2−x□x (0 ≤ x ≤ 2) of same silicon concentrations, variation of pH and the method of inverse and direct synthesis were successfully prepared first time by the theoretical maximum of incorporation of Si into the hexagonal apatite structure by precipitation method aqueous. The effects of the Si substitution on crystallite size, particle size and morphology of the powders were investigated. The crystalline phase, microstructure, morphology and particle size of hydroxyapatite and silicon substituted hydroxyapatites were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), EDX coupled with SEM and transmission electron microscopy (TEM).The samples were successfully synthesized as a single-phase apatite, and crystallization of apatite was enhanced during heating. The results obtained in this study show that the kinetics between different direct and inverse process showed different reactivities, in the presence of varying pH. Compared with the two methods, the inverse method have higher kinetic in the formation of hydroxyapatite silicate because of the difference in lattice parameters. The grain size of Si-HA samples is clearly finer than that of pure HA sample and this decreases with increasing Si content. The growth of HA nanorods with temperature can be described by “oriented attachment”. According to this theory the adjacent HA crystallites would coalesce in one particular direction on the (1 1 0) high energy planes, creating templates to form elongated rod-like structure. Fourier Transform Infrared Spectroscopy analysis reveals, the silicon incorporation to hydroxyapatite lattice occurs via substitution of silicate groups for phosphate groups. Substitution of phosphate group by silicate in the apatite structure results in a increase in the lattice parameters in both a-axis and c-axis of the unit cell.

Osteoblast interaction with laser cladded HA and SiO 2-HA coatings on Ti–6Al–4V

In order to improve the bioactivity and biocompatibility of titanium endosseous implants, the morphology and composition of the surfaces were modified. Polished Ti–6Al–4V substrates were coated by a laser cladding process with different precursors: 100 wt.% HA and 25 wt.% SiO 2-HA. X-ray diffraction of the laser processed samples showed the presence of CaTiO 3, Ca 3(PO 4) 2, and Ca 2SiO 4 phases within the coatings. From in vitro studies, it was observed that compared to the unmodified substrate all laser cladded samples presented improved cellular interactions and bioactivity. The samples processed with 25 wt.% SiO 2-HA precursor showed a significantly higher HA precipitation after immersion in simulated body fluid than 100 wt.% HA precursor and titanium substrates. The in vitro biocompatibility of the laser cladded coatings and titanium substrate was investigated by culturing of mouse MC3T3-E1 pre-osteoblast cell line and analyzing the cell viability, cell proliferation, and cell morphology. A significantly higher cell attachment and proliferation rate were observed for both laser cladded 100 wt.% HA and 25 wt.% SiO 2-HA samples. Compared to 100 wt.% HA sample, 25 wt.% SiO 2-HA samples presented a slightly improved cellular interaction due to the addition of SiO 2. The staining of the actin filaments showed that the laser cladded samples induced a normal cytoskeleton and well-developed focal adhesion contacts. Scanning electron microscopic image of the cell cultured samples revealed better cell attachment and spreading for 25 wt.% SiO 2-HA and 100 wt.% HA coatings than titanium substrate. These results suggest that the laser cladding process improves the bioactivity and biocompatibility of titanium. The observed biological improvements are mainly due to the coating induced changes in surface chemistry and surface morphology.

Part I: Crystalline Fluorapatite-Coated Hydroxyapatite, Physical Properties

Crystalline fluorapatite-coated hydroxyapatite (FA-HA) is studied using scanning electron microscopy (SEM), X-ray diffraction (XD), energy dispersive X-ray analysis (EDX), and EDX analysis mapping (EDXM). Fluoridated HA (fluorapatite) was prepared by reacting resorbable synthetic HA (OsteoGen, Impladent, Ltd, Holliswood, NY) with 4.3% sodium fluoride (NaF) for 2 minutes. After washing and drying, the resultant powder was subjected to physical property analysis using the methods listed above. SEM showed little evidence of surface change. Changes, if any, consisted of a slightly more distinct crystalline clarity on the surface of the FA sample. XD patterns showed significant random noise dispersion of the untreated HA sample compared with the lack of noise patterns in the treated FA sample. Characteristic monetite peaks were noted in analysis of the nontreated HA control sample, whereas there was no evidence of monetite in XD analysis of the treated FA material. It was determined that the fluoridation reaction, as described, served as a purification procedure of the initial HA reagent to eliminate a more soluble monetite contaminant. Also, the reaction of fluoride ion with surface HA (whether it be from or a combination of dissolution-reapposition or isomorphic substitution) produces a more purified, crystalline FA sample that was characterized by a more characteristic and sharp XD pattern. EDX analysis of the FA sample revealed a fluoride peak at 0.70 KeV that was not seen in the nonfluoridated control. EDX mapping showed an evenly distributed needle-like crystalline-shaped particulate pattern over the entire surface of the FA sample, which was lacking in the HA control. From a variety of analytic methods (as described), it was concluded that reaction of synthetic resorbable HA with 4.3% NaF solution at neutral pH produces FA-coated HA.

Thermodegradative and morphological behavior of composites of HDPE with surface-treated hydroxyapatite

In the present work, the thermodegradative and morphological behavior of composites of high-density polyethylene and surface-treated hydroxyapatite (HDPE/HA) were studied. Composites were prepared with HDPE, 30 wt% of HA and 2 phr of an ethylene–acrylic acid copolymer (20 wt% of acrylic acid) (EAA) and melt-blended in an internal mixer at 160 °C and 50 rpm. Two sets of composites filled with different surface-treated hydroxyapatite (STHA) were prepared: one HA sample was pretreated with ethylene–acrylic acid copolymer (STHA1) and the other one with acrylic acid (STHA2). Thermogravimetric analyses were carried out to evaluate the thermal stability of the composites. The activation energies (Ea) were determined using a numerical method based on the Invariant Kinetic Parameters (IKP). The thermal decomposition of the HDPE/HA composites showed an Ea value of 330 kJ/mol. On the other hand, HDPE/HA/EAA and HDPE/STHA1 composites showed a sudden decrease in Ea (272 and 270 kJ/mol, respectively). The HDPE/STHA2 composite exhibited an Ea value of 313 kJ/mol, slightly lower than that of the HDPE/HA composite. Additionally, with the presence of EAA copolymer and acrylic acid in the composites, the nucleation and nucleus growth kinetic-model probabilities decreased compared to those of the HDPE/HA composite. However, there was an increase in the probability of the reaction order of the model. This behavior could be attributed to the morphology of the composites and to the addition of a less thermally stable component, i.e. EAA copolymer and acrylic acid. On the other hand, due to the interaction polymer/surface-treated filler, an increase in the Young Modulus and the tensile strength was observed.

Fractionation and characterization of ultra-high molar mass hyaluronan: 2. On-line size exclusion chromatography methods

Present study concerns SEC fractionation of ultra-high molar mass hyaluronan. Problems in SEC of UHMM HA samples are the fractionation in the columns and the calibration of the system. We have overcome the calibration problem using absolute detectors, light scattering and viscometer, on-line to the SEC system that do not need of calibration. Shear degradation, concentration effects, viscous fingering, poor column resolution, and in general, low reproducibility are the main difficulties in SEC fractionation. A successful characterization of UHMM HA polymers requires an optimization of the experimental protocol. Each step of the experimental protocol should be performed methodically to obtain reliable results. Commercially available SEC aqueous columns have not optimized for UHMM polymers. Using an optimized SEC system shear degradation and non-ideal SEC fractionation can occur when M w of the HA sample is approximately higher than three million. Also the dispersity index could be underestimated.

1H NMR and i.r. spectroscopic investigations on soil organic fractions obtained by gel chromatography

Fulvic and humic acids fractionated by gel chromatography on Sephadex G-50 have been investigated by 1H NMR and i.r. spectroscopic techniques. Fulvic acid gives rise to only one significant fraction (FA-I) whose spectrum does not substantially differ from that of the unfractionated sample. The HA sample is separated into a high (HA-I, nominal mol. wt > 10,000) and a low molecular weight fraction (HA-II, nominal mol. wt 500–10,000). The two fractions show worthwhile differences in the 1H NMR spectra. Signals belonging to protons of long-chain aliphatic hydrocarbons or acids are present only in the HA-I fraction, which also displays a lower content of aromatic protons than the HA-II fraction. The pattern of the broad and intense absorption in the range 2.9 and 5.0 ppm of the two spectra is different. On the basis of the i.r. spectra, it has been suggested that this might be due to a different distribution of structures as polysaccharides. It seems likely that the non-humic substances are trapped in the voids of the high molecular wight polymer. The results obtained indicate that humic fractions narrower than the original material still show a high degree of polydispersity. The overall percentage distribution of chemical structures in humic fractions with varying molecular weights is different.