Calcium Crystallization Research Articles

Effect of alkali metal sulfates on hydration properties of alpha-calcium sulfate hemihydrate for 3D printing

Three-dimensional printing (3DP) technology is an important means of achieving decorative convenience, personalization, and functional integration for future building construction. However, the setting time and hydration process of calcium sulfate hemihydrate (HH) present chanllenges for the 3DP application. This study aims to investigate the accelerating effect of alkali metal sulfates accelerators on the hydration transformation of HH into calcium sulfate dihydrate (DH). The setting time, conductivity, Ca2+ ion concentration, size distribution, and zeta (ζ) potential of gypsum slurries with different accelerators were measured. The results demonstrated that the accelerators significantly enhanced the hydration process of αlpha-calcium sulfate hemihydrate (α-HH). On the effect of accelerators, the setting times of gypsum slurries containing 30 wt% lithium sulfate (LS), sodium sulfate (NS) and potassium sulfate (KS) were accelerated by 82.56 %, 86.06 % and 97.13 %, respectively, compared to the control sample. The crystal particle sizes of hydration products decreased, and the absolute values of ζ potential increased to 1.85 mV, 3.1 mV, and 5.3 mV, respectively. The X-ray photoelectron spectroscopy (XPS) analysis revealed a shift in the peak values of the hardened specimens towards higher electric fields. This was accompanied by improved ion dispersion within the slurry, resulting in enhanced supersaturation of calcium sulfate dihydrate and crystallization of the crystal nuclei. Thus, the suitable accelerators can effectively achieve rapid solidification and hardening of high-fluidity gypsum slurries.

Isolation Evaluation and Estimation of Calcium Citrate from Herbal Source

In the modern organic chemistry, various methods are now a day widely utilized for isolation of different organic compounds. From the ancient era to the present the various methods of extraction like Maceration, Percolation, Decoction and Soxhlet extraction are widely utilized. Calcium citrate also known as calcium salt of citric acid which is a member of tricarboxylic acid derivatives used occasionally as food ingredients and preservatives but it is well known source of calcium and utilized as calcium supplement. Thus the present study was initiated with aim to isolate, evaluate and estimate the calcium citrate from lemon juice by using decoction method. Calcium chloride was used for the crystallization of calcium isolated from lemon juice. Theoretical and practical yield of calcium citrate after isolation were determined. For further evaluation of isolated calcium citrate basic identification tests like solubility, melting point (MP), loss on drying (LOD) and assay of calcium citrate were done. The present study further proceeded to confirmatory evaluation by UV-Vis spectroscopy and thin layer chromatography (TLC). The basic identification tests found the presence of calcium citrate with M.P in the range of 119°C-121°C with percentage practical yield of 24.02%w/w and LOD was 9.40%. The UV-Vis absorbance shown at λ-Max 0.036 and TLC reported Rf value 0.68 and 0.53 using various polar, semipolar and non polar solvents. As ample amount of calcium citrate was isolated from herbal source i.e. lemon juice, the study reached to the conclusion that instead of synthetic sources, the herbal source can be very useful and economical approach for the isolation of calcium citrate from lemon juice.

Biological properties of hydroxyapatite coatings on titanium dioxide nanotube surfaces using negative pressure method.

Titanium (Ti) exhibits superior biocompatibility and mechanical properties but is bioinert, while hydroxyapatite (HA) possesses excellent osteogenesis and is widely used for the modification of Ti surface coatings. However, the synthesis of homogeneous and stable HA on metallic materials is still a major challenge. In this study, porous titanium dioxide nanotube arrays were prepared on Ti surface by anodic oxidation, loaded with calcium and phosphorus precursors by negative pressure immersion, and HA coating was formed by in situ crystallization of calcium and phosphorus on the surface by hydrothermal heating. Scanning electron microscopy (SEM), X-ray diffraction (XRD), and bonding strength were conducted to confirm the surface characteristics of each group. The cell proliferation, mineralization degree, and alkaline phosphatase (ALP) activity of MC3T3-E1 cells on samples were calculated and compared in vitro experiments. Cylindrical samples were implanted into rat femurs to evaluate biocompatibility and osteogenesis in vivo. The results showed that HA crystals successfully synthesized in TiO2 nanotubes, enhancing the bonding strength of HA coating and Ti substrate under negative pressure. Moreover, HA coating on Ti substrate remarkably enhanced cell proliferation and osteogenic differentiation activity in vitro, and improved new bone formation as well as osseointegration in vivo.

Enhanced nitrate, fluoride, and phenol removal using polyurethane sponges loaded with rice husk biochar in immobilized bioreactor

Polyurethane sponges loaded with rice husk biochar were prepared to immobilize Aquabacterium sp. CZ3 for intensified removal of nitrate, fluoride (F−), and phenol, with the maximum efficiency of 100 %, 91 %, and 99 %, respectively. The biochar load and increased carbon-to-nitrogen (C:N) ratio (below 3.0) stimulated the secretion of soluble microbial product, improved the electron transport system activity, and promoted denitrification, phenol co-metabolism, and F− and calcium crystallization. The characterization results suggested that F− was removed as fluoride-containing calcium precipitates. According to the microbial community analyses, Aquabacterium was the dominant bacterium. PICRUSt analyses showed that biochar and adequate carbon sources (C:N ratio 3.0) significantly increased the functional abundances of amino acid metabolism, carbohydrate metabolism, energy metabolism, and cell motility. The introduction of biochar reduces the demand for C:N ratio in the system, and expands the application potential of biomineralization technique in the remediation of multiple pollutants contaminated water.

Process intensification of atorvastatin calcium crystallization for target polymorph development via continuous combined cooling and antisolvent crystallization using an oscillatory baffled crystallizer

In this paper, continuous crystallization of Atorvastatin calcium (ASC) using a continuous oscillatory baffled crystallizer (COBC) has been investigated. Like most API manufacturing, ASC is manufactured batchwise and the pure API is recovered via batch combined cooling and antisolvent crystallization (CCAC) process, which has the challenges of low productivity, wide crystal size distribution (CSD) and sometimes polymorphic form contamination. To overcome the limitations of the batch crystallization, continuous crystallization of ASC was studied in a NiTech (United Kingdom) DN15 COBC, manufactured by Alconbury Weston Ltd. (AWL, United Kingdom), with the aim to improve productivity and CSD of the desired polymorph. The COBC has the advantage of high heat transfer rates and improved mixing that significantly reduces the crystallization time. It also has the advantage of spatial temperature distribution and multiple addition ports to control supersaturation and hence the crystallization process. This work uses an array of process analytical technology (PAT) tools to assess key process parameters that affect the polymorphic outcome and CSD. Two parameters were found to have significant impact on the polymorph, they are ratio of solvent to antisolvent at the point of mixing of the two streams and presence of seeds. The splitting of antisolvent into two addition ports in the COBC was found to give the desired form. The CCAC of ASC in COBC was found to be -30-fold more productive than the batch CCAC process. The cycle time for generating 100 g of desired polymorphic form of ASC also significantly reduced from 22 h in batch process to 12 min in the COBC. The crystals obtained using a CCAC process in a COBC had a narrower CSD compared to that from a batch crystallization process.

Atorvastatin Decreases Renal Calcium Oxalate Stone Deposits by Enhancing Renal Osteopontin Expression in Hyperoxaluric Stone-Forming Rats Fed a High-Fat Diet.

Calcium oxalate (CaOx) is the major constituent of kidney stones. Growing evidence shows a close connection between hyperlipidemia, cardiovascular disease (CVD), and the formation of kidney stones. Owing to their antioxidant properties, statins control hyperlipidemia and may ameliorate CaOx stone formation. The present study was designed to investigate the suppressive effects of statins on CaOx urolithiasis and their potential mechanism. We used rats fed a high-fat diet (HFD) to achieve hyperlipidemia (HL) and hydroxyproline (HP) water to establish a hyperoxaluric CaOx nephrolithiasis model; the animals were administered statins (A) for 28 days. The rats were divided into eight groups treated or not with A, i.e., Control, HP, HL, HL + HP. HL aggravated urinary calcium crystallization compared to the control. Due to increased expression of renal osteopontin (OPN), a key anti-lithic protein, and reduced free radical production, the calcium crystals in the urinary bladder increased as renal calcium deposition decreased. The levels of the ion activity product of CaOx (AP(CaOx)) decreased after statins administration, and AP(Calcium phosphate) (CaP) increased, which suggested the dominant calcium crystal composition changed from CaOx to CaP after statin administration. In conclusion, atorvastatin decreases renal CaOx stone deposits by restoring OPN expression in hyperoxaluric rats fed a HFD.

Petrographic Analysis of Ancient High-Temperature Ceramic Glazes and Inorganic Restoration Materials

ABSTRACT The application of scientific and technological studies prior to the repair of historic and ancient ceramics can provide a more complete understanding of glazes to aid the conservator's decision-making process before undertaking the conservation of ceramics. There are two categories of Chinese glaze morphology for general high-temperature single-color glazes, calcium glazes (smooth glazes), and calcium alkali glazes (glazes containing more bubbles or crystals and multiple glazes). High-temperature colored glazes can be divided into four types: on-glazed, in-glazed, diffused, and under-glazed pigments. The subdivision of high-temperature glaze types has significance as a guiding factor in the repair of historic and ancient ceramic glazes. Optical coherence tomography (OCT) is discussed as a non-invasive way to understand glaze structure and as a tool to aid the conservator in the treatment of ceramics. Moreover, a silica sol-acrylic composite coating was studied as a possible material to use in the replication of ceramic glazes on areas of restoration. A small amount of acrylic resin can improve the reversibility of the synthetic coating. On the macro level, this coating exhibits natural glaze bubbles and craquelure similar to historic and ancient ceramics; in addition, on the micro level, it can imitate the clean calcium glaze and crystallization calcium alkali glaze of such ceramics. The silicon oxide content in this glaze-like material is found to be similar to that of historic and ancient ceramics.

Endogenous calcium enriched hydrochar catalyst derived from water hyacinth for glucose isomerization

Water hyacinth is a major aquatic plant in ecological restoration which propagates rapidly, whereas its biomass waste lacks value-added utilization routes. To address this problem, we put forth an innovative two-step carbonization strategy to convert water hyacinth to catalyst for isomerization of glucose to fructose. Through combining the hydrothermal carbonization and pyrolysis, catalyst morphology including its carbon substrate and calcium salts was successfully engineered. The prepared hydrochar-based catalyst presented an outstanding catalytic performance, the optimal of which could obtain 31% fructose yield with 89% selectivity at 120 °C for 45 min in water and maintain the reactivity for at least three runs. The catalytic reactivity was derived from the crystallization of endogenous alkaline earth calcium in water hyacinth, which was comparable to catalysts doped with expensive metals. Besides, the equipment and energy requirements for preparation were quite low-demanding (calcined only at 400 °C for 1 h). This study not only pioneers a sustainable way to upcycle aquatic biomass, but also invents a low-cost and efficient catalyst for biorefinery through the production of engineered carbon.

Deacetylated Sp1 improves β-glycerophosphate-induced calcification in vascular smooth muscle cells.

The aging of the population has led to an annual increase in the incidence of vascular calcification (VC). Specific protein 1 (Sp1) is a transcriptional activator that serves an important role in VC. The deacetylation of transcription factors represses their binding to the promoters of downstream genes, thereby causing their downregulation. The present study aimed to investigate the role of deacetylated Sp1 in the development of VC. In the present study, western blotting and immunoprecipitation (IP) were performed to detect the protein levels of acetylated Sp1. Western blotting and immunofluorescence staining were used to analyze phenotypic switching in vascular smooth muscle cells (VSMCs). Alizarin red S, alkaline phosphatase (ALP) activity and calcium content assays were used to assess calcium deposition in VSMCs. Western blotting, flow cytometry, TUNEL staining and caspase3 activity assay were used to evaluate apoptosis of VSMCs. Chromatin immunoprecipitation (ChIP) assay was used to detect Sp1 binding to the BMP2 promoter. The results indicated that, in a β-glycerophosphate (β-GP)-induced VSMC calcification model, the level of acetylated Sp1 was increased. Western blotting and immunofluorescence staining results showed that, compared with the Sp1 overexpression group (Sp1-WT), deacetylated Sp1 (Sp1-K704A) downregulated the expression of osteogenic markers runt-related transcription factor 2 (Runx2) and bone morphogenetic protein 2 (BMP2), and upregulated the expression of contraction marker α-smooth muscle actin (α-SMA) and calponin 1. In addition, deacetylated Sp1 also reduced the ALP activity and calcium content of calcified VSMCs, and the Alizarin red S assay revealed that the calcium crystallization of Sp1-K704A group was markedly decreased. Western blotting, flow cytometry, TUNEL staining and caspase-3 activity assay were detected to indicate that the B-cell lymphoma 2 (Bcl-2)/Bcl-2-associated X protein ratio was increased, and caspase-3 activity and the apoptotic rate of VSMCs were decreased, in the Sp1-K704A group, as compared with the Sp1-WT group. ChIP assay revealed that Sp1 binding to the BMP2 promoter was downregulated in the Sp1-K704A group, compared with that in theSp1-WT group. In conclusion, a deacetylated mutant of Sp1 decreased Sp1 binding to the BMP2 promoter, thus decreasing apoptosis, phenotypic switching and calcium deposition in calcified VSMCs. This finding may indicate potential therapeutic targets for VC.

Complex character of the influence of polycarboxylic and phosphonic acids on the crystallization of calcium and magnesium salts in dynamic conditions

The influence of water-soluble organic compounds (adipic, polyaspartic and phosphonic acids) and their compositions on the crystallization of calcium and magnesium salts in dynamic conditions has been studied. It is found that the induction period of phase formation increases in the presence of polyaspartic and phosphonic acids 2.3–5.2 times in the range of their content from 0.05 to 0.2 ppm. The results of XRD and electron microscopic studies confirm the change in the phase composition and morphology of the crystalline precipitate that is formed. The dibasic carboxylic acid influence on the induction period, composition and structure of the precipitate is much less. It is established that the composition of organic acids also increases the induction period of phase formation. The complex inhibitor provides an increase in the critical supersaturation level in the system. The phosphonic and carboxyl groups of the inhibitor interact with calcium and magnesium ions and block the crystallization nuclei. When interacting with the dicarboxylic acid and polyacid adsorption on the surface of the formed crystals, the microcrystals dissolve.

Effect of mechanical activation on extraction of vanadium from chromium-containing vanadate solution by calcification and carbonization

The effect of mechanical activation on extraction of vanadium from chromium-containing vanadate solution by precipitation with calcium salt and leaching with sodium carbonate salt was investigated. The whole process including selective precipitation of vanadium, alkali leaching of vanadium and cyclic utilization of calcium. Compared with stirring, ball milling is more effective for vanadium precipitation under the same experiment conditions. This is because the calcium vanadate formed on the surface of Ca(OH)2 can be peeled off by mechanical activation, which can also be confirmed by SEM image, EDS spectra and XRD patterns of the precipitation. The effect of temperature ranging from 20 °C to 50 °C on vanadium leaching efficiency was studied with the other reaction conditions fixed as stirring speed of 400 r/min, NaHCO3/V molar ratio of 2.80, L/S ratio of 4:1 ml/g. It is observed that vanadium leaching efficiency exceeding 99% was obtained after only 6 min of reaction as well as leaching temperature had little influence on vanadium leaching efficiency. After filtration, the leach solution was used to prepare crystals of NH4VO3 and the leach residue was calcined to obtain CaO. The precipitation efficiency of V was 99.34% by adding CaO into chromium-containing vanadate solution according to Ca/V molar ratio 1.80 and ball milling for 90 min with 140 rpm at room temperature. Mechanical activation can not only increase the vanadium precipitation efficiency and improve the leaching performance of the precipitate, but also to realize the cyclic utilization of calcium salt and crystallization solution.

METASTATIC PULMONARY CALCIFICATION: A RARE CAUSE OF PULMONARY HYPERTENSION

SESSION TITLE: Fellows Pulmonary Vascular Disease Posters SESSION TYPE: Fellow Case Report Posters PRESENTED ON: October 18-21, 2020 INTRODUCTION: Metastatic calcification is seen at autopsy in 60-75% of CKD patients on hemodialysis (HD) due to increased calcium phosphate product (normal 40 mg2/dl2; MPC >70 mg2/dl2) (1,2). Metastatic pulmonary calcification associated with pulmonary hypertension (PH) is rare. We present a case of MPC associated combined postcapillary and precapillary PH (CpcPH). CASE PRESENTATION: A 58-year-old woman with SLE, CTD-ILD (FVC 64%, TLC 56 %), ESRD on HD since 2008 and diastolic heart failure was admitted to the hospital with worsening dyspnea, leg edema and orthopnea. Her calcium phosphate product was 61. CT chest showed diffuse ground glass opacity with mosaic perfusion, enlarged pulmonary artery (PA 4.3 cm) and chest wall calcifications. Echocardiogram showed grade 3 diastolic dysfunction, severely dilated left atrium and elevated right ventricular systolic pressure. Heart catheterization showed mean PA pressure 62 mm Hg, PA wedge pressure 29 mm Hg, transpulmonary gradient (TPG) 33, diastolic pulmonary gradient (DPG) 11, pulmonary vascular resistance 9 WU, LV end diastolic pressure 27 mm Hg, cardiac output 3.6, cardiac index 2.1. Given her severe PH, low CI and NYHA functional class IV, she was started on inhaled treprostinil with improvement in leg edema and orthopnea at 6-month follow up. DISCUSSION: Hyperphosphatemia in ESRD causes increased calcium phosphate product leading to calcium crystallization. Metastatic calcifications are usually seen in lamina propria of stomach, lung alveoli, renal tubules and interstitium(2). Acidosis between HD sessions causes leaching of calcium from bone, leading to deposition during post dialysis alkalosis. Uremia alters the configuration of tissue protein, rendering them more calcifiable. Three main CT patterns of MPC include centrilobular ground glass nodules, dense consolidation and small dense nodules(1). It is usually peripheral in distribution with upper lung zone dominance due to increased alkalinity (higher V/Q ratio causing low PaCO2) causing calcium salt deposition. Vascular calcification in chest and abdominal wall is a common finding as noted in our case. 30-50% of CKD and ESRD patients have PH. Vascular calcification can affect pulmonary arterial capacitance (low PAC in our case 0.81) and increase RV afterload. In this case, contributing factors to her PH are elevated LVEDP, ILD and ESRD (WHO group II, III and V). TPG >12 and DPG >7 suggested pulmonary vascular remodeling from shear stress and downstream pressure. This is an interesting case of MPC with associated PH. Initiation of the pulmonary vasodilator treprostinil reduced her PVR allowing for a better coupling of the RV-PA system. CONCLUSIONS: Treatment of MPC includes intensification of HD sessions and use of calcium and phosphate binders. In this case, inhaled pulmonary vasodilators for treatment of CpcPH after medical treatment optimization of other co-morbidities led to symptomatic improvement. Reference #1: Metastatic pulmonary calcification: HRCT findings in 23 cases, Radiol Bras.2017 Jul-Aug; 50(4): 231–236 Reference #2: Metastatic pulmonary calcification: State-of-the-art review focused on imaging findings, Respiratory Medicine Feb 2014 (108): 668-676 Reference #3: Pulmonary hypertension with extensive calcification in small pulmonary vessels and alveolar capillary wall in a chronic hemodialysis patient, Journal of Cardiology Cases 8 (Feb 2013) e13–e16 DISCLOSURES: No relevant relationships by Moises Cossio, source=Web Response No relevant relationships by Domingo Franco-Palacios, source=Web Response No relevant relationships by Kushagra Gupta, source=Web Response No relevant relationships by Shahzad Hussain, source=Web Response No relevant relationships by Venkateswara Kollipara, source=Web Response No relevant relationships by Toribiong Uchel, source=Web Response

Comparison with Crystallization of Calcium and Strontium Carbonates under DPPC Langmuir Monolayers

In this paper, using Langmuir monolayers of dipalmitoylphosphatidylcholine (DPPC) as template, we have investigated the controlled crystallization of calcium and strontium carbonates to understand the biomineralization process at the inorganic-organic interface better. Although the calcite with a well-oriented (104) crystal plane has been obtained, as for the strontium carbonates, DPPC monolayers have resulted in the formation of the flower-like assemblies of strontianite needles; however, the oriented growth under the monolayers has not appeared. Using the lattice matching and electrostatic interaction at the inorganic-organic interface, we have discussed the possible mechanism of the phenomena.

Influence of various uropathogens on crystallization of urine mineral components caused by Proteus mirabilis

Infectious urolithiasis is a consequence of long-standing urinary tract infections with urease-positive bacteria, especially Proteus spp. However, because of the often mixed nature of urinary tract infections, in the case of urinary stones formation, several species of bacteria may be involved in the process. The purpose of the study was to determine the impact of the bacterial species: Escherichia coli, Klebsiella pneumoniae, Providencia stuartii, Pseudomonas aeruginosa and Staphylococcus aureus on the crystallization caused by Proteus mirabilis. The studies were conducted in synthetic urine with the addition of P. mirabilis and a representative of another species. During the experiments the viability of bacteria, pH, presence and morphology of crystals, and the intensity of crystallization were assessed. Crystallization of calcium and magnesium phosphates occurred in all investigated configurations. However, there were differences observed in the course and intensity of crystallization between the mixed culture and the P. mirabilis culture. Although most intense crystallization took place in the pure culture of P. mirabilis it was also demonstrated that the presence of other uropathogens increased the survival of P. mirabilis. This synergistic effect could be responsible for the persistence and recurrence of urolithiasis in the urinary tract.

Influence of mesophilic and thermophilic conditions on the anaerobic digestion of food waste: Focus on the microbial activity and removal of long chain fatty acids.

The mesophilic reactor (MR) exhibited advantages in biogas production and performance stability over thermophilic reactor (TR) during the long-term anaerobic digestion (AD) of food waste (FW) with stepwise organic loading rate elevating. It was interesting to explore the mechanism causing the divergences in performances between these two reactors. The microbial activity was compared on day 110 when TR began to deteriorate. The results show that MR had significantly higher specific acetoclastic methanogenic activities (SAMA) and specific propionate and butyrate oxidative activities (SPOA and SBOA) than TR. The SAMA, SPOA and SBOA in TR were only 50.3%, 18.6% and 46.4% of those values in MR, respectively. Remarkably, the specific hydrogenotrophic methanogenic activity of 15.5±2.1, 15.7±4.6 mmol CH4·L-1 original slurry·d-1 in MR and TR was comparative with insignificant difference, which indicates that the microbial activity in TR had been inhibited widely apart from the hydrogenotrophic methanogenesis. Additionally, many particles with the diameters of 1-2 mm were observed to form in MR and identified as complexes of calcium and long chain fatty acids (LCFAs). The formation of calcium crystallization might alleviate the inhibition of LCFAs during AD of FW, which further supports the better performance in MR than TR.

Size, shape, and identity of surface crystals and their relationship to sensory perception of grittiness in soft smear-ripened cheeses

Soft smear-ripened cheeses undergo extensive surface crystallization and radial demineralization of calcium, magnesium, and phosphorus, which likely contributes to radial softening during ripening. Furthermore, anecdotal evidence suggests that grittiness is a common characteristic of smear-ripened cheeses. The primary aims of the present study were to evaluate the intensity of perceived grittiness while assessing other key sensory attributes in US artisanal and European protected designation of origin smear-ripened cheeses, and to relate perceived grittiness to the size, shape, and identity of crystals present in the cheese surface smears. Fully ripened wheels of 24 different varieties of smear-ripened cheeses, 16 produced in the United States and 8 in the European Union, were obtained from retail sources. A trained sensory panel (n = 12) was employed to evaluate intensity of grittiness. Crystals present in the cheese smears were identified by powder X-ray diffractometry and polarized light microscopy, and further evaluated in polarized light microscopy micrographs by image analysis for size and shape characteristics. Mean sensory scores for the 24 cheeses ranged from no perceived grittiness to easily identifiable grittiness. Surface crystals included ikaite, struvite, calcite, and brushite, and mean crystal length and area ranged among cheeses from 27 to 1,096 μm, and 533 to 213,969 μm2, respectively. Panel threshold for grittiness occurred at a mean crystal length of about 66 μm and mean crystal area of about 2,913 μm2. Cheeses with mean values at or below these thresholds displayed negligible perceived grittiness. In contrast, for cheeses with mean values above these thresholds, the mean sensory scores for grittiness were highly correlated with mean crystal length and crystal area (r = 0.93 and 0.96, respectively). Results suggest that surface crystals in soft smear-ripened cheeses influence sensory perception of texture in complex ways that likely include radial softening and grittiness development. A better understanding of factors that govern surface crystal formation may lead to improved control over crystallization and more consistent cheese texture.

Separate Crystallization of Lanthanide Oxalates and Calcium Oxalates from Nitric Acid Solutions

The separation of lanthanides from calcium compounds in the form of oxalates from hot nitric acid solutions of Ln(NO3)3 and Ca(NO3)2 with the insertion of oxalic acid and a Ln2(C2O4)3 · nH2O crystal seed was studied by mass-spectrometric, atomic emission, microscopic, X-ray diffraction, and fluorescence analyses. The produced single-phase precipitate was found to contain an isomorphic impurity of La–Sm oxalates, while calcium oxalate remained in the hot nitric acid solution (95°С) saturated with oxalic acid. This facile and efficient method provides Ln2(C2O4)3 · nH2O (n = 9.5 mol) in one step in a 80.1 rel. % yield, with the major phase being at least 99.4 wt %. The unit cell parameters were determined for the crystals of the isomorphic lanthanide oxalate mixture: a = 11.243(2) A, b = 9.591(2) A, c = 10.306(2) A; α = γ = 90°, β = 114.12(1)°; Z = 2; V = 1013.7(5) A3.

Real-Time Monitoring of Urinary Encrustation Using a Quartz Crystal Microbalance.

Encrustation on the surface of urological devices such as ureteral stents leads to their blockage. However, limited tools are available for fast and real-time monitoring and modeling of the encrustation process. In this work, we have developed a model for in vitro study of encrustation and coupled it to an online monitoring QCM technique. The QCM biosensor is precoated with a polymer that is representative of the surface of a ureteral stent and subsequently coated with urease to facilitate crystallization of calcium and magnesium phosphate. The changes in deposition of crystals on the polymer surface are monitored quantitatively using a quartz crystal microbalance (QCM) biosensor. The QCM sensor is capable of dynamic, label-free detection and has a very high sensitivity. Experimental data generated using this model shows that pretreatment of the sensor surface with urease significantly induces early stage encrustation as compared to the untreated sensor surface, which emulates the real encrustation process. This encrustation study model has a high utility in screening studies for materials used in urological devices.

Oligogalacturonic Acid Inhibits Vascular Calcification by Two Mechanisms: Inhibition of Vascular Smooth Muscle Cell Osteogenic Conversion and Interaction With Collagen.

Cardiovascular diseases constitute the leading cause of mortality worldwide. Calcification of the vessel wall is associated with cardiovascular morbidity and mortality in patients having many diseases, including diabetes mellitus, atherosclerosis, and chronic kidney disease. Vascular calcification is actively regulated by inductive and inhibitory mechanisms (including vascular smooth muscle cell adaptation) and results from an active osteogenic process. During the calcification process, extracellular vesicles (also known as matrix vesicles) released by vascular smooth muscle cells interact with type I collagen and then act as nucleating foci for calcium crystallization. Our primary objective was to identify new, natural molecules that inhibit the vascular calcification process. We have found that oligogalacturonic acids (obtained by the acid hydrolysis of polygalacturonic acid) reduce in vitro inorganic phosphate-induced calcification of vascular smooth muscle cells by 80% and inorganic phosphate-induced calcification of isolated rat aortic rings by 50%. A specific oligogalacturonic acid with a degree of polymerization of 8 (DP8) was found to inhibit the expression of osteogenic markers and, thus, prevent the conversion of vascular smooth muscle cells into osteoblast-like cells. We also evidenced in biochemical and immunofluorescence assays a direct interaction between matrix vesicles and type I collagen via the GFOGER sequence (where single letter amino acid nomenclature is used, O=hydroxyproline) thought to be involved in interactions with several pairs of integrins. DP8 inhibits vascular calcification development mainly by inhibition of osteogenic marker expression but also partly by masking the GFOGER sequence-thereby, preventing matrix vesicles from binding to type I collagen.

Aluminum-induced dreierketten chain cross-links increase the mechanical properties of nanocrystalline calcium aluminosilicate hydrate

The incorporation of Al and increased curing temperature promotes the crystallization and cross-linking of calcium (alumino)silicate hydrate (C-(A-)S-H), which is the primary binding phase in most contemporary concrete materials. However, the influence of Al-induced structural changes on the mechanical properties at atomistic scale is not well understood. Herein, synchrotron radiation-based high-pressure X-ray diffraction is used to quantify the influence of dreierketten chain cross-linking on the anisotropic mechanical behavior of C-(A-)S-H. We show that the ab -planar stiffness is independent of dreierketten chain defects, e.g. vacancies in bridging tetrahedra sites and Al for Si substitution. The c -axis of non-cross-linked C-(A-)S-H is more deformable due to the softer interlayer opening but stiffens with decreased spacing and/or increased zeolitic water and Ca2+ of the interlayer. Dreierketten chain cross-links act as ‘columns’ to resist compression, thus increasing the bulk modulus of C-(A-)S-H. We provide the first experimental evidence on the influence of the Al-induced atomistic configurational change on the mechanical properties of C-(A-)S-H. Our work advances the fundamental knowledge of C-(A-)S-H on the lowest level of its hierarchical structure, and thus can impact the way that innovative C-(A-)S-H-based cementitious materials are developed using a ‘bottom-up’ approach.