Calcium Hydrogen Phosphate Dihydrate Research Articles

Incorporate biosafe additives into self-healing coating on Mg for enhanced interfacial biocompatibility recovery

Local defects in coatings allow aggressive electrolytes penetrate to the coating/substrate interface, accelerating the corrosion of the exposed Mg substrate and compromising its biocompatibility. In this work, self-healing calcium hydrogen phosphate dihydrate (DCPD) coating incorporated with 3,5-dinitrosalicylic acid (3,5-D) or 5-amino salicylic acid (5-A) is designed on Mg. The results reveal that the self-healing and corrosion resistance performance of DCPD improves after adding 3,5-D/5-A. Namely, incorporating 3,5-D/5-A into DCPD accelerates the self-healing process and repair the coating at the initial stage. The released 3,5-D/5-A additives could adsorb on the exposed Mg surface and combine with the Ca2+ ions to precipitate. The interfacial adsorption mechanism of 3,5-D/5-A additives is disclosed by quantum chemical calculation. The simultaneously responsive adsorption and deposition of additives during coating degradation increase the thickness and compactness of the deposition layer at the coating defects, further inhibiting corrosion and stabilizing pH. These findings suggest taking biocompatibility recovery into consideration of preparing self-healing coating for biomedical applications.

Continuous synthesis of calcium hydrogen phosphate dihydrate (DCPD) in an annular rotating flow loop reactor

The synthesis of calcium hydrogen phosphate dihydrate (DCPD) involves a gas–liquid-solid three-phase slurry system that poses challenges for precise control using traditional batch reactors to produce crystals with controlled morphologies and particle sizes. In this study, an annular rotating flow loop reactor (ARLR) was developed to continuously synthesize DCPD. The unique internal loop and annular rotating flow field of the reactor delivered exceptional plug-flow characteristics, ensuring that the obtained DCPD exhibited a controlled morphology and particle size. The morphology of DCPD was adjusted to be bowknot-shaped (BS) agglomerate crystals, reaching a length of 120 μm and a D50 size of 70 μm. The ARLR can achieve long-term stable operation with high-solid holdup slurries, outputting up to 125 g/h by maintaining precise and controllable flow and mixing conditions. Notably, ARLR marked a significant advancement in processing high-solid-holdup slurries, offering the adaptability to adjust the geometric design for various slurry systems and forecasting promising prospects.

Inhibitory Effect of Alternanthera Sessilis, Cucurbita Maxima and Aerva Lanata on Whewellite Urinary Crystals

Phosphate stones, such as struvite (magnesium ammonium phosphate hexahydrate), brushite (calcium hydrogen phosphate dihydrate), and oxalates like whewellite (calcium oxalate monohydrate) are different kinds of urinary stones. Such kidney stones can be treated with herbs for natural healing and side effects-free results. These urinary crystals are traditionally created in the lab using the gel growth process and a silica gel medium at a specified pH. The inhibitory effects can be analysed by using the extracts of herbal plants. In the present study, ethanol extracts of leaves of Alternanthera sessilis, seeds of Cucurbita maxima and flowers of Aerva lanata are investigated for their inhibitory activity against the whewellite urinary crystals. They are characterized using Fourier transform infrared spectrum and their crystalline nature is examined through powder X-ray diffraction. Asymmetric and symmetric stretching unit of C=O in oxalate appears at 1620 cm-1 and 1400, 1310 cm-1 respectively. The monoclinic crystal system with a space group of P21/n is confirmed from the powder X-ray diffraction studies. The results indicated that among the three ethanol extracts, leaves of Alternanthera sessilis, seeds of Cucurbita maxima and flowers of Aerva lanata- the flowers of Aerva lanata exhibited inhibition towards whewellite crystals. KEYWORDS Extract, flowers, herbs, oxalates, pH, seeds

Compaction Properties of Particulate Proteins in Binary Powder Mixtures with Common Excipients.

The increasing interest in protein- and peptide-based oral pharmaceuticals has culminated in the first protein-based products for oral delivery becoming commercially available. This study investigates the compaction properties of proteins in binary mixtures with common excipients up to 30% (w/w) of particulate protein. Two model proteins, lysozyme and bovine serum albumin, were compacted with either microcrystalline cellulose, spray-dried lactose monohydrate, or calcium hydrogen phosphate dihydrate at two different compaction pressures. Compared to the compacted pure materials, a significant increase in the tensile strength of the compacts was observed for the binary blends containing lysozyme together with the brittle excipients. This could be attributed to the increased bonding forces between the particles in the blend compared to the pure materials. The use of bovine serum albumin with a larger particle size resulted in a decrease in tensile strength for all the compacts. The change in the tensile strength with an increasing protein content was non-linear for both proteins. This work highlights the importance of considering the particulate properties of protein powders and that protein-based compacts can be designed with similar principles as small-molecules in terms of their mechanical tablet properties.

Sensitivity of a bone-equivalent polymer gel dosimeter for measuring the dose to bone during radiation therapy.

Treatment planning systems that use the Monte Carlo algorithm can calculate the dose to the medium (Dm) in non-water-equivalent tissues such as bones. However, Dm cannot be verified using actual measurements; therefore, it is necessary to develop tissue-equivalent dosimeters. In this study, we developed a bone-equivalent polymer gel dosimeter (BPGD) that can measure the dose absorbed by the bone and investigated its sensitivity. The BPGDs were prepared by adding 3.0mol of calcium hydrogen phosphate dihydrate as a component of bone to an improved dose-sensitive polyacrylamide gelatin and tetrakis hydroxymethyl phosphonium chloride (iPAGAT). One day after preparation, the BPGDs were irradiated with a field size of 15 × 15 cm2 using a 10 MV X-ray beam to evaluate the dose sensitivity, dose-rate dependence, and dose-integration dependence. One day after dose exposure, the BPGDs were scanned using a 0.4T MRI APERTO Eterna (Hitachi, Tokyo, Japan) to obtain R2 values. The difference between the R2 values of 6Gy and 0Gy was up to 5s-1, and the R2 curve plateaued in the high-dose region. Moreover, the BPGD did not depend on the integration of the dose and dose rates. Therefore, the BPGDs that we developed can determine the radiation dose to bones.

Comparison of bovine serum albumin and chitosan effects on calcium phosphate formation in the presence of silver nanoparticles.

The precipitation of calcium phosphates (CaPs) in the presence of more than one type of additive is of interest both from a fundamental point of view and as a possible biomimetic route for the preparation of multicomponent composites in which the activity of the components is preserved. In this study, the effect of bovine serum albumin (BSA) and chitosan (Chi) on the precipitation of CaPs in the presence of silver nanoparticles (AgNPs) stabilized with sodium bis(2-ethylhexyl)sulfosuccinate (AOT-AgNPs), poly(vinylpyrrolidone) (PVP-AgNPs), and citrate (cit-AgNPs) was investigated. In the control system, the precipitation of CaPs occurred in two steps. Amorphous calcium phosphate (ACP) was the first precipitated solid, which transformed into a mixture of calcium-deficient hydroxyapatite (CaDHA) and a smaller amount of octacalcium phosphate (OCP) after 60 min of ageing. Both biomacromolecules inhibited ACP transformation, with Chi being a stronger inhibitor due to its flexible molecular structure. As the concentration of the biomacromolecules increased, the amount of OCP decreased both in the absence and presence of AgNPs. In the presence of cit-AgNPs and two highest BSA concentrations, a change in the composition of the crystalline phase was observed. Calcium hydrogen phosphate dihydrate was formed in the mixture with CaDHA. An effect on the morphology of both the amorphous and crystalline phases was observed. The effect depended on the specific combination of biomacromolecules and differently stabilized AgNP. The results obtained suggest a simple method for fine-tuning the properties of precipitates using different classes of additives. This could be of interest for the biomimetic preparation of multifunctional composites for bone tissue engineering.

Physico-geometrical kinetic insight into multistep thermal dehydration of calcium hydrogen phosphate dihydrate.

The origin of the multistep thermal dehydration of calcium hydrogen phosphate dihydrate (dibasic calcium phosphate dihydrate (DCPD)) to form γ-calcium diphosphate (γ-calcium pyrophosphate (γ-CPP)) via calcium hydrogen phosphate anhydride (dibasic calcium phosphate anhydride (DCPA)) was investigated from a specific viewpoint of physico-geometrical constraints generated during the reaction. The overall thermal dehydration was separated into five partially overlapping steps through systematic kinetic analysis. The first three steps and the residual two steps were attributed to the thermal dehydration of DCPD to form DCPA and of DCPA to form γ-CPP, respectively. The first to third steps were kinetically characterized by the surface reaction of plate-like particles controlled by nucleation and growth, the movement of the reaction interface inward to the plate by releasing water vapor through voids formed in the surface product layer, and the rapid escape of water vapor accompanied by the cleavage of plate-like particles into slices, respectively. The contributions of each component step varied with the heating conditions and atmospheric water vapor pressure. The subsequent dehydration of DCPA proceeded in two steps by the release of trapped water molecules in amorphous DCPA induced by its gradual crystallization and the dehydration of DCPA to form poorly crystalline γ-CPP, which continued to grow during the fifth mass loss step and exhibited a detectable exothermic phenomenon after the mass loss was completed. The possible causes of the variation in the multistep reaction features with reaction conditions were discussed by correlating the kinetic analysis results with the crystallographic and morphological findings.

Near-Infrared Absorption Coefficients in Kidney Stone Minerals and Their Relation to Crystal Structure

To quantitatively understand laser ablation of kidney stones by near-infrared (NIR) lasers, accurate measurements of physical properties related to heating and mechanical failure are needed. While light scattering varies among individual stones, absorption coefficients for the materials that form the bulk of each kidney stone are measurable when scattering is controlled. We developed methods to grow single crystals with lengths and widths >20 μm for the minerals that form kidney stones: calcium oxalate monohydrate, calcium oxalate dihydrate, calcium hydrogen phosphate dihydrate, hydroxyapatite, anhydrous uric acid, and magnesium ammonium phosphate hexahydrate. These single crystals were used with an infrared microscope to measure their NIR absorption coefficients from 1.67 to 2.5 μm. The strong correlation between single crystal NIR spectra and diffuse reflectance NIR spectra indicates little anisotropy in absorption. Most minerals absorbed more strongly at 1.94 μm than 2.12 μm, the wavelengths of thulium fiber and holmium:YAG surgical lasers, respectively. For water bearing minerals, we attribute absorption mainly to water combination modes and assign NIR absorption peaks to specific water molecules and the OH bonds thereof where possible. Reported absorption coefficients can be used to quantitatively compare both laboratory investigations of ablation and surgical experience to physical properties for the first time.

Structure and Properties of Bioactive Glass-Modified Calcium Phosphate/Calcium Sulfate Biphasic Porous Self-Curing Bone Repair Materials and Preliminary Research on Their Osteogenic Effect.

In this study, calcium phosphate (CP)/calcium sulfate biphasic bone repair materials were modified with bioactive-glass (BG) to construct a self-curing bone repair material. Tetracalcium phosphate, calcium hydrogen phosphate dihydrate, and calcium sulfate hemihydrate (CSH) with different BG ratios and phosphate solution were reacted to prepare a porous self-curing bone repair material (CP/CSH/BG). The solidification time was about 12 min, and the material was morphologically stable in 24 h. The porosity was about 50%, with a pore size around 200 μm. The strength of CP/CSH/BG was approaching trabecular bone, and could be gradually degraded in Tris-HCl solution. MC3T3-E1 cells were cultured in the leaching solution of the materials. Cytotoxicity was detected using Cell Counting Kit 8 assays, and the expression of osteogenesis-related biomarkers was detected using quantitative real-time reverse transcription PCR (qRT-PCR). The results showed that all BG groups had increased ALP and ARS staining, implying that the BG groups could promote osteoblast mineralization in vitro. qRT-PCR showed significant upregulation of bone-related gene expression (Osx, Ocn, Runx2, and Col1) in the 20% BG group (p < 0.05). Therefore, the CP/CSH/BG self-curing bone repair materials can promote osteogenesis, and might be applied for bone regeneration, especially for polymorphic bone defect repair.

Analytical Evaluation of Wet and Dry Mechanochemical Syntheses of Calcium-Deficient Hydroxyapatite Containing Zinc Using X-ray Diffractometry and Near-Infrared Spectroscopy.

Calcium-deficient zinc-containing calcium phosphate (ZnAP), which has sustained zinc release properties that are effective for treating osteoporosis, can be efficiently synthesized as a biomaterial through wet grinding. To elucidate the physicochemical mechanism of these mechanochemical syntheses, ground products were obtained from the starting material powder (S-CP), consisting of calcium hydrogen phosphate dihydrate (CHPD), calcium oxide (CaO), and zinc oxide (ZnO), by wet and dry grinding for 0–3 h in a centrifugal ball mill. The ground S-CP products were analyzed using powder X-ray diffraction (XRD) and near-infrared spectroscopy (NIRS); the crystal transformations and molecular interactions of the ground products were kinetically analyzed. The XRD and second-derivative NIRS results indicate that the S-CP is primarily transformed into ZnAP via amorphous solid formation in wet grinding, and the reaction follows a consecutive reaction model. In contrast, in dry grinding, the ground product of CHPD and CaO is transformed into an amorphous solid following an equilibrium reaction model; however, ZnO is predominantly not transformed and remains crystalline.

How Reliable Is Endoscopic Stone Recognition? A Comparison Between Visual Stone Identification and Formal Stone Analysis.

Objective: To assess the diagnostic accuracy and intra-observer agreement of endoscopic stone recognition (ESR) compared with formal stone analysis. Introduction: Stone analysis is a corner stone in the prevention of stone recurrence. Although X-ray diffraction (XRD) and infrared spectroscopy are the recommended techniques for reliable formal stone analysis, this is not always possible, and the process takes time and is costly. ESR could be an alternative, as it would give immediate information on stone composition. Materials and Methods: Fifteen endourologists predicted stone composition based on 100 videos from ureterorenoscopy. Diagnostic accuracy was evaluated by comparing the prediction from visual assessment with stone analysis by XRD. After 30 days, the videos were reviewed again in a random order to assess intra-observer agreement. Results: The median diagnostic accuracy for calcium oxalate monohydrate was 54% in questionnaire 1 (Q1) and 59% in questionnaire 2 (Q2), whereas calcium oxalate dihydrate had a median diagnostic accuracy of 75% in Q1 and 50% in Q2. The diagnostic accuracy for calcium hydroxyphosphate was 10% in Q1 and 13% in Q2. The median diagnostic accuracy for calcium hydrogen phosphate dihydrate and calcium magnesium phosphate was 0% in both questionnaires. The median diagnostic accuracy for magnesium ammonium phosphate was 20% in Q1 and 40% in Q2. The median diagnostic accuracy for uric acid was 22% in both questionnaires. Finally, there was a diagnostic accuracy of 60% in Q1 and 80% in Q2 for cystine. The intra-observer agreement ranged between 45% and 72%. Conclusion: Diagnostic accuracy of ESR is limited and intra-observer agreement is below the threshold of acceptable agreement.

Recrystallization of Triple Superphosphate Produced from Oyster Shell Waste for Agronomic Performance and Environmental Issues

Calcium dihydrogen phosphate monohydrate (Ca(H2PO4)2·H2O) (a fertilizer) was successfully synthesized through a recrystallization process using prepared triple superphosphate (TSP) derived from oyster shell waste as the starting material. This bio-green, eco-friendly process to produce an important fertilizer can promote a sustainable society. The shell-waste-derived TSP was dissolved in distilled water and kept at 30, 50, and 80 °C. Non-soluble powder and TSP solution were obtained. The TSP solution fractions were then dried, and the recrystallized products (RCP30, RCP50, and RCP80) were obtained and confirmed as Ca(H2PO4)2·H2O. Conversely, the non-soluble products (NSP30, NSP50, and NSP80) were observed as calcium hydrogen phosphate dihydrate (CaHPO4·2H2O). The recrystallized yields of RCP30, RCP50, and RCP80 were found to be 51.0%, 49.6%, and 46.3%, whereas the soluble percentages were 98.72%, 99.16%, and 96.63%, respectively. RCP30 shows different morphological plate sizes, while RCP50 and RCP80 present the coagulate crystal plates. X-ray diffractograms confirmed the formation of both the NSP and RCP. The infrared adsorption spectra confirmed the vibrational characteristics of HPO42−, H2PO4−, and H2O existed in CaHPO4·2H2O and Ca(H2PO4)2·H2O. Three thermal dehydration steps of Ca(H2PO4)2·H2O (physisorbed water, polycondensation, and re-polycondensation) were observed. Ca(H2PO4)2 and CaH2P2O7 are the thermodecomposed products from the first and second steps, whereas the final product is CaP2O6.

Detection of the mineral constituents in human renal calculi by vibrational spectroscopic analysis combined with allied techniques Powder XRD, TGA, SEM, IR imaging and TXRF

Detection of the mineral constituents in a batch of 310 samples of human urinary calculi (kidney stones-235 and bladder stones-75) combined with a semi-quantitative analysis has been presented on the basis of Fourier Transform based IR and Raman spectral measurements. Some of the observed characteristic IR and Raman bands have been proposed as ‘Marker Bands’ for the most reliable identification of the constituents. A detailed vibrational spectral analysis combined with a DFT level calculation for the functional groups in Calcium Oxalate Monohydrate (COM), Magnesium Ammonium Phosphate Hexahydrate (MAPH), Calcium Hydrogen Phosphate Dihydrate (CHPD), Penta-Calcium Hydroxy-Triphosphate (PCHT) and Uric Acid (UA) has been proposed. It has been shown that the identified mineral constituents as major or minor components can be deduced from the application of Lambert-Beer law of radiation absorption and results are in agreement with quantitative Spectral Data base. This simple method has the potential to be integrated into the management of Urolithiasis, a process of forming renal calculi in the kidney, bladder and/or urethra. Employment of powder XRD, TGA, SEM, TXRF and IR Imaging techniques has provided additional support for the proposed foolproof identification of the mineral constituents. Among the mineral constituents, Calcium Oxalate Monohydrate, Calcium Oxalate Dihydrate or their mixture account for 85% of the total number of samples; the remaining 15% and 5% samples contain Phosphate and Uric acid stones respectively.

COPPER WHITLOCKITE SYNTHESIZED VIA HYDROTHERMAL TRANSFORMATION OF CALCIUM HYDROGEN PHOSPHATE DIHYDRATE

Metal ion substitution in calcium phosphate provides a vehicle for therapeutic delivery of metal ions at low cost and with a long shelf life. The whitlockite structure can incorporate metal ions, which enables the introduction of antibacterial and antiviral agents such as copper ions. The present study describes the synthesis of copper whitlockite (CuWH) via a single-step hydrothermal transformation of calcium hydrogen phosphate dihydrate in the presence of copper ions. Hexahedral morphology of single-phase CuWH was synthesized at 220 °C for 12 h at pH 2.0 in the presence of 5 to 7 mol% Cu2+ ions, suggesting that CuWH precipitation was both dose- and pH-dependent. The CuWH structure contained protonated phosphate, which also suggests that Cu2+ ions were incorporated not only into the Ca(5) site but also the Ca(4) site. The dissolution test mimicking a bioresorption environment created by osteoclasts showed similar dissolution characteristics of Ca2+ and Cu2+ ions in acetic acid–sodium acetate buffer solution containing potassium nitrate at pH 5.5.

Studies on the pH-Dependent Solubility of Various Grades of Calcium Phosphate-based Pharmaceutical Excipients

Calcium phosphate-based pharmaceutical excipients, including calcium hydrogen phosphate anhydrous and dihydrate, calcium hydroxide phosphate have been well established in pharmaceutical technology for a very long time. Nowadays, they are of increasing interest to the pharmaceutical industry because, in addition to their advanced functional properties, they offer beneficial biocompatible and biodegradable properties. Yet, there is limited availability of embracing information regarding the solubility of these popular excipients, especially in variable pH conditions, reflecting those of the gastrointestinal tract (GIT). The study has shown that the solubility of calcium phosphates as well as their dissolution rate decreases significantly with increasing pH of dissolution fluids. The highest solubility was observed for dibasic calcium phosphate dihydrate, the lowest for tribasic calcium phosphate. This article provides also a comparison of various calcium phosphate types originating from different manufacturers, which may prove to be useful and help formulation scientists to design new medicinal products.

Evaluating the use of calcium hydrogen phosphate dihydrate as a mineral‐based fire retardant for application in melamine‐urea‐formaldehyde (MUF)‐bonded wood‐based composite materials

SummaryCalcium hydrogen phosphate dihydrate (DCPD) was evaluated for its potential as a mineral fire retardant (FR) for application in melamine‐urea‐formaldehyde (MUF)‐bonded wood composites. The efficacy as FR was studied in melamine‐urea‐formaldehyde (MUF)‐bonded three‐layer particleboard as a function of addition quantities of 10‐, 20‐ and 30 wt%. Resistance to fire and mechanical properties were determined by measuring the self‐extinguishing time after flame exposure and internal bond strength, respectively. Combustion behavior was examined on samples with 20 wt% DCPD addition by performing cone calorimetry experiments. The efficacy of DCPD was evaluated by determining the heat release, total heat release rate, smoke production, and smoke production rate and compared to another promising mineral‐based fire‐retardant composition (FRC) based on hydroxyapatite (HA) with deliquescent salt and HA alone. The effect of FR on the curing behavior of MUF in relation to mechanical properties was determined through viscosity measurements of MUF with 10 wt% addition of FR. The results confirmed the fire‐retardant characteristics of DCPD in wood composites, albeit at higher application rates when compared to the FRC, however with no negative impact on resin curing time or mechanical strength. Based on the demonstrated compatibility in MUF, DCPD is considered a promising mineral extender of other FRs for application in UF‐based wood composites.

Evolution and performance of a MgO/HA/DCPD gradient coating on pure magnesium

A composite calcium phosphate (CaPh) coating containing calcium hydrogen phosphate dihydrate (DCPD) and hydroxyapatite (HA) is fabricated on plasma electrolytic oxidized (PEO) magnesium via electro-assisted deposition. During immersion in simulated body fluid, the soluble DCPD stimulates the precipitation of HA and remains the degradability of the system, while the stable HA reinforces the corrosion resistance along with PEO layer. The morphology, thickness and corrosion property of the coating evolve remarkably with the deposition time. Various growth patterns of DCPD are presented in different period which noticeably influences the interfacial combination, as well as corrosion resistance. The composite coating after 60 min deposition shows most compact morphology and stable interfacial combination, leading to excellent corrosion resistance, apatite formation ability and cell attachment behavior.

Investigation on the impact of different proportions of components in formulations on stability of a moisture sensitive drug

Physicochemical and mechanical properties of tablets are largely dictated by formulation compositions. Different excipients possess different tableting and moisture sorption behaviors. Therefore, this study was designed to elucidate the relative influence of the proportion of components in formulations on tablet properties. Acetylsalicylic acid (ASA) tablets containing different proportions of starch, microcrystalline cellulose (MCC) and calcium hydrogen phosphate dihydrate (DCP) were prepared. The excipients were evaluated for their moisture sorption properties. Mechanical strength of the tablets was determined alongside with ASA stability, by storing the tablets at 75% RH, 25 °C. The stability study showed the importance of drug loading level on its stability. For a fixed ASA proportion, formulations with more starch were able to absorb more moisture and possessed larger areas of hysteresis loop in their moisture sorption isotherms. The presence of starch contributed positively to ASA stability although increasing proportions of starch compromised the tablet mechanical properties. Contrastingly, MCC produced mechanically stronger tablets as its plastically deforming and fibrous properties contributed to a good structural network. The findings provide a deeper understanding of the dichotomous effect by the proportion of components in formulations containing a moisture sensitive drug on drug stability and mechanical strength of the resultant tablets.

Effect of Aegle marmelos on the growth of brushite crystals

BackgroundThe urinary stone formation is a very common health problem due to the prolonged medication. Calcium Hydrogen Phosphate Dihydrate (CaHPO4.2H2O, CHPD and Brushite) is one of the major constituent of urinary stone crystals. The formation and deposition of brushite crystals is the central cause of recurrent kidney stone disease among the global population. The present study aims to investigate the effect of Aegle marmelos leaves on the growth of brushite crystals to explicate the inhibitory effect of urinary stones from a different point of view.MethodsThe CHPD crystals were grown by the Single Diffusion Gel growth technique. In order to inhibit the formation of urinary stones, CHPD crystals are grown in the laboratory in the pure form and by adding the prolonged medicine A. marmelos taken especially by diabetic patients. A comparative study of the pure and A. marmelos leaves added crystals has been carried out using the Growth factor, Powder X-ray diffraction, Microstructural parameters, FTIR and SEM-EDAX.ResultsTotal mass of the grown crystals is found to decrease with increasing concentrations of leaf extract of the A. marmelos. On comparing with undoped, crystalline size of the A. marmelos doped samples is reduced. Disappearance of absorption band and peak shift in the FTIR shows the incorporation of functional groups of A. marmelos. The morphology changes of the treated crystals are assessed in SEM.ConclusionsThe result shows that herbal extracts prepared from A. marmelos have good inhibitory effect on the growth of the brushite urinary stone crystals considered.

Formation and corrosion behaviors of calcium phosphate coatings on plasma electrolytic oxidized Mg under changing chemical environment

Abstract In order to form calcium phosphate (CaPh) coatings in the changing chemical environment, a drop wise addition procedure is performed during electro-deposition process. Two kind of electrolytes of KH2PO4 and K2HPO4, are added into Ca(NO3)2 solution respectively where plasma electrolytic oxidized (PEO) magnesium is placed. Results indicate that the phase composition and morphologies of the CaPh coatings are modified due to the changing chemical composition of electrolyte. Only calcium hydrogen phosphate dihydrate (DCPD) is formed on the PEO surface in the presence of KH2PO4 electrolyte, while a combination of hydroxyapatite (HA) and DCPD is obtained on the PEO surface in the electrolyte containing K2HPO4. The latter coating exhibits superior corrosion resistance in simulated body fluid, which implies the feasibility of the proposed strategy in fabricating biodegradable coating for Mg alloys.