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Ab initio insight into the physical properties of MgXH3 (X = Co, Cu, Ni) lead-free perovskite for hydrogen storage application

Rehman ZU, Rehman MA, Rehman B, Sikiru S, Qureshi S, Ali EM, et al.

Environ Sci Pollut Res Int, 2023 Nov;30(53):113889-113902.
PMID: 37858013 DOI: 10.1007/s11356-023-30279-0

Renewable energy systems are vital for a sustainable future, where solid-state hydrogen storage can play a crucial role. Perovskite hydride materials have attracted the scientific community for hydrogen storage applications. The current work focuses on the theoretical study using density functional theory (DFT) to evaluate the characteristics of MgXH3 (X = Co, Cu, Ni) hydrides. The structural, vibrational, electronic, mechanical, thermodynamic, and hydrogen storage properties of these hydrides were investigated. The equilibrium lattice parameters were calculated using the Birch-Murnaghan equation of state-to-energy volume curves. The elastic constants (Cij) and relevant parameters, such as Born criteria, were calculated to confirm the mechanical stability of the hydrides. The Cauchy pressure (Cp) revealed brittle or ductile behavior. The outcomes of the Pugh ratio, Poisson ratio, and anisotropy were also calculated and discussed. The absence of negative lattice vibrational frequencies in phonon dispersion confirmed the lattice's dynamic stability. The heat capacity curves of thermodynamic properties revealed that hydrides can conduct thermal energy. The metallic character and ample interatomic distances of hydrides were confirmed by the band structure and population analysis, which confirmed that hydrides can conduct electrical energy and adsorb hydrogen. The density of state (DOS) and partial DOS unveiled the role of specific atoms in the DOS of the crystal. The calculated gravimetric hydrogen storage capacity of MgCoH3, MgCuH3, and MgNiH3 hydrides was 3.64, 3.32, and 3.49wt%, respectively. Our results provide a deeper understanding of its potential for hydrogen storage applications through a detailed analysis of MgXH3 (X = Co, Cu, Ni) perovskite hydride material.

Matched MeSH terms: Calcium Compounds*
Photoelectrical Dynamics Uplift in Perovskite Solar Cells by Atoms Thick 2D TiS2 Layer Passivation of TiO2 Nanograss Electron Transport Layer

Alias N, Ali Umar A, Malek NAA, Liu K, Li X, Abdullah NA, et al.

ACS Appl Mater Interfaces, 2021 Jan 20;13(2):3051-3061.
PMID: 33410652 DOI: 10.1021/acsami.0c20137

A deficiency in the photoelectrical dynamics at the interface due to the surface traps of the TiO2 electron transport layer (ETL) has been the critical factor for the inferiority of the power conversion efficiency (PCE) in the perovskite solar cells. Despite its excellent energy level alignment with most perovskite materials, its large density of surface defect as a result of sub lattice vacancies has been the critical hurdle for an efficient photovoltaic process in the device. Here, we report that atoms thick 2D TiS2 layer grown on the surface of a (001) faceted and single-crystalline TiO2 nanograss (NG) ETL have effectively passivated the defects, boosting the charge extractability, carrier mobility, external quantum efficiency, and the device stability. These properties allow the perovskite solar cells (PSCs) to produce a PCE as high as 18.73% with short-circuit current density (Jsc), open-circuit voltage (Voc), and fill-factor (FF) values as high as 22.04 mA/cm2, 1.13 V, and 0.752, respectively, a 3.3% improvement from the pristine TiO2-NG-based PSCs. The present approach should find an extensive application for controlling the photoelectrical dynamic deficiency in perovskite solar cells.

Matched MeSH terms: Calcium Compounds
Fulltext Mechanical and in vitro biological performance of graphene nanoplatelets reinforced calcium silicate composite

Mehrali M, Moghaddam E, Seyed Shirazi SF, Baradaran S, Mehrali M, Latibari ST, et al.

PLoS One, 2014;9(9):e106802.
PMID: 25229540 DOI: 10.1371/journal.pone.0106802

Calcium silicate (CaSiO3, CS) ceramic composites reinforced with graphene nanoplatelets (GNP) were prepared using hot isostatic pressing (HIP) at 1150°C. Quantitative microstructural analysis suggests that GNP play a role in grain size and is responsible for the improved densification. Raman spectroscopy and scanning electron microscopy showed that GNP survived the harsh processing conditions of the selected HIP processing parameters. The uniform distribution of 1 wt.% GNP in the CS matrix, high densification and fine CS grain size help to improve the fracture toughness by ∼130%, hardness by ∼30% and brittleness index by ∼40% as compared to the CS matrix without GNP. The toughening mechanisms, such as crack bridging, pull-out, branching and deflection induced by GNP are observed and discussed. The GNP/CS composites exhibit good apatite-forming ability in the simulated body fluid (SBF). Our results indicate that the addition of GNP decreased pH value in SBF. Effect of addition of GNP on early adhesion and proliferation of human osteoblast cells (hFOB) was measured in vitro. The GNP/CS composites showed good biocompatibility and promoted cell viability and cell proliferation. The results indicated that the cell viability and proliferation are affected by time and concentration of GNP in the CS matrix.

Matched MeSH terms: Calcium Compounds/chemistry*
Kinetics and thermodynamic analysis in one-pot pyrolysis of rice hull using renewable calcium oxide based catalysts

Gan DKW, Loy ACM, Chin BLF, Yusup S, Unrean P, Rianawati E, et al.

Bioresour Technol, 2018 Oct;265:180-190.
PMID: 29894912 DOI: 10.1016/j.biortech.2018.06.003

Thermodynamic and kinetic parameters of catalytic pyrolysis of rice hull (RH) pyrolysis using two different types of renewable catalysts namely natural limestone (LS) and eggshells (ES) using thermogravimetric analysis (TG) approach at different heating rates of 10-100 K min-1 in temperature range of 323-1173 K are investigated. Catalytic pyrolysis mechanism of both catalysts had shown significant effect on the degradation of RH. Model free kinetic of iso-conversional method (Flynn-Wall-Ozawa) and multi-step reaction model (Distributed Activation Energy Model) were employed into present study. The average activation energy was found in the range of 175.4-177.7 kJ mol-1 (RH), 123.3-132.5 kJ mol-1 (RH-LS), and 96.1-100.4 kJ mol-1 (RH-ES) respectively. The syngas composition had increased from 60.05 wt% to 63.1 wt% (RH-LS) and 63.4 wt% (RH-ES). However, the CO2 content had decreased from 24.1 wt% (RH) to 20.8 wt% (RH-LS) and 19.9 wt% (RH-ES).

Matched MeSH terms: Calcium Compounds/chemistry*
Carbide lime as substrates to boost energy recuperation and dyestuff removal in constructed wetland-microbial fuel cell integrated with copper oxide/carbon cloth cathode

Leow GY, Lam SM, Sin JC, Zeng H, Li H, Huang L, et al.

Environ Sci Pollut Res Int, 2024 Apr;31(16):23647-23663.
PMID: 38427169 DOI: 10.1007/s11356-024-32637-y

Methylene blue (MB) was regarded as a highly toxic and hazardous substance owing to its irreparable hazard and deplorable damage on the ecosystem and the human body. The treatment of this colorant wastewater appeared to be one of the towering challenges in wastewater treatment. In this study, a microbial fuel cell coupled with constructed wetland (CW-MFC) with effective MB elimination and its energy recuperation concurrently based on the incorporation of carbide lime as a substrate in a new copper oxide-loaded on carbon cloth (CuO/CC) cathode system was studied. The crucial influencing parameters were also delved, and the MB degradation and chemical oxygen demand (COD) removal efficiencies were correspondingly incremented by 97.3% and 89.1% with maximum power output up to 74.1 mW m-2 at optimal conditions (0.2 g L-1 carbide lime loading and 500 Ω external resistance). The carbide lime with high calcium ion content was greatly conducive for the enrichment of critical microorganism and metabolic activities. The relative abundances of functional bacteria including Proteobacteria and Actinobacteriota were vividly increased. Moreover, the impressive results obtained in printed ink wastewater treatment with a COD removal efficiency of 81.3% and a maximum power density of 58.2 mW m-2, which showcased the potential application of CW-MFC.

Matched MeSH terms: Calcium Compounds*
Long-term evaluation of palm oil mill effluent (POME) steam reforming over lanthanum-based perovskite oxides

Cheng YW, Chong CC, Cheng CK, Wang CH, Ng KH, Witoon T, et al.

J Environ Manage, 2024 Feb;351:119919.
PMID: 38157572 DOI: 10.1016/j.jenvman.2023.119919

To replace the obsolete ponding system, palm oil mill effluent (POME) steam reforming (SR) over net-acidic LaNiO3 and net-basic LaCoO3 were proposed as the POME primary treatments, with promising H2-rich syngas production. Herein, the long-term evaluation of POME SR was scrutinized with both catalysts under the optimal conditions (600 °C, 0.09 mL POME/min, 0.3 g catalyst, & 74-105 μm catalyst particle size) to examine the catalyst microstructure changes, transient process stability, and final effluent evaluation. Extensive characterization proved the (i) adsorption of POME vapour on catalysts before SR, (ii) deposition of carbon and minerals on spent SR catalysts, and (iii) dominance of coking deactivation over sintering deactivation at 600 °C. Despite its longer run, spent LaCoO3 (50.54 wt%) had similar carbon deposition with spent LaNiO3 (50.44 wt%), concurring with its excellent coke resistance. Spent LaCoO3 (6.12 wt%; large protruding crystals) suffered a harsher mineral deposition than spent LaNiO3 (3.71 wt%; thin film coating), confirming that lower reactivity increased residence time of reactants. Transient syngas evolution of both SR catalysts was relatively steady up to 4 h but perturbed by coking deactivation thereafter. La2O2CO3 acted as an intermediate species that hastened the coke removal via reverse Boudouard reaction upon its decarbonation. La2O2CO3 decarbonation occurred continuously in LaCoO3 system but intermittently in LaNiO3 system. LaNiO3 system only lasted for 13 h as its compact ash blocked the gas flow. LaCoO3 system lasted longer (17 h) with its porous ash, but it eventually failed because KCl crystallites blocked its active sites. Relatively, LaCoO3 system offered greater net H2 production (72.78%) and POME treatment volume (30.77%) than LaNiO3 system. SR could attain appreciable POME degradation (>97% COD, BOD5, TSS, & colour intensity). Withal, SR-treated POME should be polished to further reduce its incompliant COD and BOD5.

Matched MeSH terms: Calcium Compounds*
Photocatalytic treatment of palm oil mill effluent by visible light-active calcium ferrite: Effects of catalyst preparation technique

Charles A, Cheng CK

J Environ Manage, 2019 Mar 15;234:404-411.
PMID: 30640165 DOI: 10.1016/j.jenvman.2019.01.024

Palm oil mill effluent (POME) is a serious and expensive environmental problem in Malaysia. In this paper, CaFe2O4 is introduced as a novel photocatalyst for the degradation of POME under visible light irradiation. Two synthesis routes, auto-combustion and co-precipitation, and two calcination temperatures 550 °C and 700 °C were used to produce four CaFe2O4 catalysts AC550, AC700, CP550 and CP700. CP550 exhibited the greatest photocatalytic degradation at 56% chemical-oxygen-demand (COD) removal after 8 h of irradiation which dropped to 49% after three consecutive cycles indicating reasonable conversion and high recyclability. BET analysis indicated CP550 had the highest SBET (27.28 m2/g) and pore volume (0.077 cm3/g) which dropped precipitously for CP700 upon increasing the calcination temperature to an SBET of 9.73 m2/g and pore volume of 0.025 cm3/g due to annealing which created a smoother surface area as evidenced by the SEM images. UV-Vis DRS indicated CP550 had the highest band-gap (1.52 eV) which is likely due to the presence of a highly crystalline pure CaFe2O4 phase compared to the other products which existed as a mixture of Fe oxidation states evidenced by the XRD data. The PL spectra for all catalysts indicated significantly lower recombination rate for both CP550 and CP700. Introduction of IPA into the reaction mixture to eliminate hydroxyl radicals resulted in a diminishing of COD removal from 56% to 7% proving hydroxyl radicals to be the primary reactive species responsible for photodegradation of POME.

Matched MeSH terms: Calcium Compounds
Fulltext Analysis of glass fracture pattern on soda lime and tempered glass caused by shotgun bullet impact

Dahshaini Nadarajan, Sharifah Mastura Syed Mohd Daud, Nadiah Syariani Md Shariff

Malaysian Journal of Medicine and Health Sciences, 2020;16(101):131-135.
MyJurnal

Introduction: Broken glass exhibits unique fracture patterns depend upon the nature of the impact. The fracture patterns provide information like point and angle of impact, direction of force and sequence of firing. Recent studies have shown that the use of shotgun in Malaysia is increasing, yet, the relationship existing among the fracture pattern and the projectile impact factors are not well documented. The objective was to analyse the fracture characteristics on different glass types of variable thickness and distance made by shotgun ammunition. Methods: Soda lime and tempered glass panel with dimension of 12’x 12’ with 3 or 4 mm thickness were shot from various distances of 4, 6 and 8 m from the muzzle end of the shotgun. Samples were analysed under fixed parameters and observations were recorded. Results: It is found that the bullet hole diameter of 4 mm tempered glass were larger compared to 4 mm soda lime glass ranged from 14.33 to 24.17 cm as distance increased. Tempered glass surface also exhibited dicing fragments unlike soda lime glass where only radial fracture patterns are evident. This can be attributed to high inherent strength and ductility that makes the tempered glass remarkably resistant to external force. Conclusion: The findings from this study can lead to distinguish the type of glass through examination of fracture patterns, whether it is soda lime silica or tempered glass. The type of glass and the source of impact can be determined using the fragments, no reconstruction necessary.

Matched MeSH terms: Calcium Compounds
Fulltext Are patients satisfied with hospital food?

Teng, Sang-Chong, Esah Bahaman, Tang, Wen-Yen

Malaysian Journal of Public Health Medicine, 2003;3(1):52-56.
MyJurnal

Although only 6.3% of the 221 respondents in this crass-sectional study stated outright that the hospital food served to them was not good, a high proportion of respondents ( 62.0%) supplemented ltaspimlfoad with outside food. When the reasons for supplementation were considered, it is likely that 53.8% ( $5.5%; 95% CI ) of the patients in this study were dissatisfied with hospimlfoudfar some reasons or when particularly with regards t0 variety, attractiveness and sewing lime. The pl‘0]701’l‘i011 of respondents wha were dissatisfied with hospital faud was significantly higher (p

Matched MeSH terms: Calcium Compounds
Fulltext Bandgap tuning of mixed organic cation utilizing chemical vapor deposition process

Kim J, Kim HP, Teridi MA, Yusoff AR, Jang J

Sci Rep, 2016 11 22;6:37378.
PMID: 27874026 DOI: 10.1038/srep37378

Bandgap tuning of a mixed organic cation perovskite is demonstrated via chemical vapor deposition process. The optical and electrical properties of the mixed organic cation perovskite can be manipulated by varying the growth time. A slight shift of the absorption band to shorter wavelengths is demonstrated with increasing growth time, which results in the increment of the current density. Hence, based on the optimized growth time, our device exhibits an efficiency of 15.86% with negligible current hysteresis.

Matched MeSH terms: Calcium Compounds
Fulltext Influence of discrete fibers and mesh elements on the behaviour of lime stabilized soil

Kaniraj, Shenbaga R., Fung, Y. C.

Pertanika Journal of Science & Technology, 2018;26(4):1547-1570.
MyJurnal

Addition of chemical binders such as lime and cement improves the strength and stiffness
of fine grained soils. However, the treated soils exhibit brittle stress-strain behaviour.
Inclusion of randomly oriented discrete fibers in the soil-binder mixture changes its brittle
behaviour into ductile behaviour. Most synthetic fibers, however, tend to get entangled
and cannot be easily separated from one another. Therefore, it is difficult to realize soilbinder-
fiber mixtures in which the fibers are distributed uniformly throughout the mass.
This issue has been an impediment in the utilization of the positive modification in the
behaviours of soils and soil-binder mixtures by the fibers. The present study aims to address
the limitations in using fibers as soil reinforcement. Further, it also aims to investigate
the use of synthetic mesh or net elements as an alternative type of soil reinforcement.
The paper presents the experimental study on a fine grained soil. Lime has been chosen
as the binder due to its low cost and the scarcity of fiber reinforced soil studies in which
lime has been used as a binder. The main experimental program is a series of unconfined
compression tests on samples prepared using untreated soil, soil-reinforcement mixture,
soil-lime mixture, and soil-lime-reinforcement mixture. The lime treated samples were
cured up to 120 days at laboratory temperature. The results demonstrate the combinational
effects of lime and discrete reinforcement
elements on the behaviour and mechanical
properties of the soil. The performances of
the fiber and mesh element reinforcements
have also been compared.

Matched MeSH terms: Calcium Compounds
Fulltext Wetting/Drying Behavior of Lime and Alkaline Activation Stabilized Marine Clay Reinforced with Modified Coir Fiber

Kamaruddin FA, Anggraini V, Kim Huat B, Nahazanan H

Materials (Basel), 2020 Jun 17;13(12).
PMID: 32560432 DOI: 10.3390/ma13122753

The durability of natural and treated clay soil stabilized with lime and alkaline activation (AA) affected by environmental factors (hot and humid) was determined in this study. Investigation and evaluation on the strength of the soil, moisture content, and volume change of the specimen were determined at each curing period (7, 28, and 90 days) based on the weather conditions. An unconfined compressive strength (UCS) of the specimen at three different wetting/drying cycles (one, three, and five cycles) was determined. The findings show that the strength of the treated specimens fluctuated with increment and decrement strength (one and three cycles) in the range of 1.41 to 1.88 MPa (lime) and 2.64 to 8.29 MPa (AA), while for five cycles with a curing period of 90 days the decrement was in the range of 1.62 to 1.25 MPa and 6.06 to 5.89 MPa for lime and AA, respectively. The decrement percentage for treated samples that were subjected to five cycles of wetting and drying in 90 days was found to be 20.38% (lime) and 38.64% (AA), respectively. Therefore, it can be summarized that wetting/drying cycles have a significant influence on the durability, strength, and the volume changes of the specimens.

Matched MeSH terms: Calcium Compounds
Fulltext Demonstration of chemistry at a point through restructuring and catalytic activation at anchored nanoparticles

Neagu D, Papaioannou EI, Ramli WKW, Miller DN, Murdoch BJ, Ménard H, et al.

Nat Commun, 2017 11 30;8(1):1855.
PMID: 29187751 DOI: 10.1038/s41467-017-01880-y

Metal nanoparticles prepared by exsolution at the surface of perovskite oxides have been recently shown to enable new dimensions in catalysis and energy conversion and storage technologies owing to their socketed, well-anchored structure. Here we show that contrary to general belief, exsolved particles do not necessarily re-dissolve back into the underlying perovskite upon oxidation. Instead, they may remain pinned to their initial locations, allowing one to subject them to further chemical transformations to alter their composition, structure and functionality dramatically, while preserving their initial spatial arrangement. We refer to this concept as chemistry at a point and illustrate it by tracking individual nanoparticles throughout various chemical transformations. We demonstrate its remarkable practical utility by preparing a nanostructured earth abundant metal catalyst which rivals platinum on a weight basis over hundreds of hours of operation. Our concept enables the design of compositionally diverse confined oxide particles with superior stability and catalytic reactivity.

Matched MeSH terms: Calcium Compounds
Fulltext Design and Development for Capacitive Humidity Sensor Applications of Lead-Free Ca,Mg,Fe,Ti-Oxides-Based Electro-Ceramics with Improved Sensing Properties via Physisorption

Tripathy A, Pramanik S, Manna A, Bhuyan S, Azrin Shah NF, Radzi Z, et al.

Sensors (Basel), 2016 Jul 21;16(7).
PMID: 27455263 DOI: 10.3390/s16071135

Despite the many attractive potential uses of ceramic materials as humidity sensors, some unavoidable drawbacks, including toxicity, poor biocompatibility, long response and recovery times, low sensitivity and high hysteresis have stymied the use of these materials in advanced applications. Therefore, in present investigation, we developed a capacitive humidity sensor using lead-free Ca,Mg,Fe,Ti-Oxide (CMFTO)-based electro-ceramics with perovskite structures synthesized by solid-state step-sintering. This technique helps maintain the submicron size porous morphology of the developed lead-free CMFTO electro-ceramics while providing enhanced water physisorption behaviour. In comparison with conventional capacitive humidity sensors, the presented CMFTO-based humidity sensor shows a high sensitivity of up to 3000% compared to other materials, even at lower signal frequency. The best also shows a rapid response (14.5 s) and recovery (34.27 s), and very low hysteresis (3.2%) in a 33%-95% relative humidity range which are much lower values than those of existing conventional sensors. Therefore, CMFTO nano-electro-ceramics appear to be very promising materials for fabricating high-performance capacitive humidity sensors.

Matched MeSH terms: Calcium Compounds
Fulltext Tunable Open Circuit Voltage by Engineering Inorganic Cesium Lead Bromide/Iodide Perovskite Solar Cells

Ng CH, Ripolles TS, Hamada K, Teo SH, Lim HN, Bisquert J, et al.

Sci Rep, 2018 02 06;8(1):2482.
PMID: 29410450 DOI: 10.1038/s41598-018-20228-0

Perovskite solar cells based on series of inorganic cesium lead bromide and iodide mixture, CsPbBr3-xI x , where x varies between 0, 0.1, 0.2, and 0.3 molar ratio were synthesized by two step-sequential deposition at ambient condition to design the variations of wide band gap light absorbers. A device with high overall photoconversion efficiency of 3.98 % was obtained when small amount of iodide (CsPbBr2.9I0.1) was used as the perovskite and spiro-OMeTAD as the hole transport material (HTM). We investigated the origin of variation in open circuit voltage, Voc which was shown to be mainly dependent on two factors, which are the band gap of the perovskite and the work function of the HTM. An increment in Voc was observed for the device with larger perovskite band gap, while keeping the electron and hole extraction contacts the same. Besides, the usage of bilayer P3HT/MoO3 with deeper HOMO level as HTM instead of spiro-OMeTAD, thus increased the Voc from 1.16 V to 1.3 V for CsPbBr3 solar cell, although the photocurrent is lowered due to charge extraction issues. The stability studies confirmed that the addition of small amount of iodide into the CsPbBr3 is necessarily to stabilize the cell performance over time.

Matched MeSH terms: Calcium Compounds
Nanostructuring Mixed-Dimensional Perovskites: A Route Toward Tunable, Efficient Photovoltaics

Koh TM, Shanmugam V, Schlipf J, Oesinghaus L, Müller-Buschbaum P, Ramakrishnan N, et al.

Adv Mater, 2016 May;28(19):3653-61.
PMID: 26990287 DOI: 10.1002/adma.201506141

2D perovskites is one of the proposed strategies to enhance the moisture resistance, since the larger organic cations can act as a natural barrier. Nevertheless, 2D perovskites hinder the charge transport in certain directions, reducing the solar cell power conversion efficiency. A nanostructured mixed-dimensionality approach is presented to overcome the charge transport limitation, obtaining power conversion efficiencies over 9%.

Matched MeSH terms: Calcium Compounds
A theoretical investigation of the lead-free double perovskites halides Rb2 XCl6 (X = Se, Ti) for optoelectronic and thermoelectric applications

Al-Qaisi S, Mebed AM, Mushtaq M, Rai DP, Alrebdi TA, Sheikh RA, et al.

J Comput Chem, 2023 Jul 15;44(19):1690-1703.
PMID: 37093704 DOI: 10.1002/jcc.27119

In this study, structural, electronic, optical, thermoelectric, and thermodynamics properties of vacancy-ordered double perovskites Rb2 XCl6 (X = Se, Ti) were explored theoretically. The results revealed that Rb2SeCl6 and Rb2 TiCl6 are indirect band gap (Eg ) semiconductors with Eg values of 2.95 eV, and 2.84 eV respectively. The calculated properties (phonons, elastic constant, Poisson's ratio, and Pugh's ratio) revealed that both materials are dynamically and chemically stable and can exhibit brittle (Rb2 SeCl6 ) and ductile (Rb2 TiCl6 ) nature. From the analysis of optical parameters, it was noticed that the refractive index of the materials has a value of 1.5-2.0 where light absorption was found from the visible to the ultraviolet region. The thermoelectric properties determined by using the BoltzTrap code demonstrated that at room temperature, the Figure of merit (ZT) was found to be 0.74 and 0.76 for Rb2 SeCl6 and Rb2 TiCl6 , respectively. Despite a moderate value of ZT in such materials, further studies might explore effective methods for tuning the electronic band gap and improving the thermoelectric response of the material for practical energy production applications.

Matched MeSH terms: Calcium Compounds
Influence of long -term thermal cycling and masticatory loading simulation on bond strength of roots filled with epoxy resin and calcium silicate based sealers

Smran A, Abdullah M, Ahmad NA, Alrahlah A, Al-Maflehi N, Samran A

BMC Oral Health, 2023 Sep 18;23(1):673.
PMID: 37723511 DOI: 10.1186/s12903-023-03377-1

BACKGROUND: The aim of this study was to evaluate the effect of thermal and mechanical cyclic aging using a mastication simulator on push-out bond strength of mandibular premolars obturated with AH Plus and BioRoot RCS root canal sealers.
METHODS: With REVO-S files up to SU/0.06 taper, 48 single-rooted premolar teeth were instrumented. The teeth were randomly divided into two main groups (n = 24) based on the two root canal sealers used (AH Plus and BioRoot RCS). All teeth were obturated with h matched-taper single-cone. Each main group was then subdivided into three subgroups (A, B, and C) (n = 8). Group A served as the negative control group (no-thermocycling aging). While groups B and C were subjected to thermal changes in a thermocycler machine (15,000 and 30,000 thermal cycles, respectively), followed by two different dynamic loading periods, 3 × 105 and 6 × 105 in a masticatory simulator with a nominal load of 5 kg at 1.2 Hz which represent roughly 1½ and 3 years of clinical function respectively. 2 mm slice at 3 levels, apical, middle, and coronal, to obtain 3 sections were prepared and subjected to push-out test using a universal testing machine. Statistical analysis was performed using analysis of variance (ANOVA) followed by a Tukey post hoc comparisons test and an independent T-test. A significance level of 5% was used.
RESULTS: After thermal-mechanical cyclic aging, the two root canal sealers showed a significantly decreased in push-out bond strength (p

Matched MeSH terms: Calcium Compounds
Fulltext A comparison in mechanical properties of cermets of calcium silicate with Ti-55Ni and Ti-6Al-4V alloys for hard tissues replacement

Ataollahi Oshkour A, Pramanik S, Shirazi SF, Mehrali M, Yau YH, Abu Osman NA

ScientificWorldJournal, 2014;2014:616804.
PMID: 25538954 DOI: 10.1155/2014/616804

This study investigated the impact of calcium silicate (CS) content on composition, compressive mechanical properties, and hardness of CS cermets with Ti-55Ni and Ti-6Al-4V alloys sintered at 1200°C. The powder metallurgy route was exploited to prepare the cermets. New phases of materials of Ni16Ti6Si7, CaTiO3, and Ni31Si12 appeared in cermet of Ti-55Ni with CS and in cermet of Ti-6Al-4V with CS, the new phases Ti5Si3, Ti2O, and CaTiO3, which were emerged during sintering at different CS content (wt%). The minimum shrinkage and density were observed in both groups of cermets for the 50 and 100 wt% CS content, respectively. The cermets with 40 wt% of CS had minimum compressive Young's modulus. The minimum of compressive strength and strain percentage at maximum load were revealed in cermets with 50 and 40 wt% of CS with Ti-55Ni and Ti-6Al-4V cermets, respectively. The cermets with 80 and 90 wt% of CS showed more plasticity than the pure CS. It concluded that the composition and mechanical properties of sintered cermets of Ti-55Ni and Ti-6Al-4V with CS significantly depend on the CS content in raw cermet materials. Thus, the different mechanical properties of the cermets can be used as potential materials for different hard tissues replacements.

Matched MeSH terms: Calcium Compounds/chemistry*
Fulltext Effect of ZnO on the physical properties and optical band gap of soda lime silicate glass

Zaid MH, Matori KA, Aziz SH, Zakaria A, Ghazali MS

Int J Mol Sci, 2012;13(6):7550-8.
PMID: 22837711 DOI: 10.3390/ijms13067550

This manuscript reports on the physical properties and optical band gap of five samples of soda lime silicate (SLS) glass combined with zinc oxide (ZnO) that were prepared by a melting and quenching process. To understand the role of ZnO in this glass structure, the density, molar volume and optical band gaps were investigated. The density and absorption spectra in the Ultra-Violet-Visible (UV-Visible) region were recorded at room temperature. The results show that the densities of the glass samples increased as the ZnO weight percentage increased. The molar volume of the glasses shows the same trend as the density: the molar volume increased as the ZnO content increased. The optical band gaps were calculated from the absorption edge, and it was found that the optical band gap decreased from 3.20 to 2.32 eV as the ZnO concentration increased.

Matched MeSH terms: Calcium Compounds/chemistry*

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