IR@CGCRI - Central Glass and Ceramic Research Institute (CSIR)
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Unlocking the Potential: Algal Biomass Cultivation and Growth Kinetics Using Tanning Process Water
No full textA basic kinetic model has been applied to microalgae to predict the growth parameters in Zarrouk Media composition (ZMC) and precipitated chrome tanning effluent (PCTE). The model was fitted with the experimental data of Spirulina cultivation to estimate growth parameters: nutrient adsorption constant (Ka) (h–1), nutrient desorption constant (Kd) (h–1), rate of respiration (rRc)(h–1), efficiency of bio-synthesis (β) (g g–1), respiration rate (h–1)(rRc), rate of maximum photosynthesis (pmax) (h–1), coefficient for light-absorption (α) (m2 g–1), photon efficiency (g.μmol–1 photons–1) (φm), etc. The model suggests a higher nutrient adsorption rate in ZMC (0.75 h–1) as compared to PCTE (1.40 × 10–2 h–1). The rate of respiration of Spirulina decreased due to cultivation in PCTE from 5.36 × 10–3 to 1.91 × 10–3 h–1. The biosynthetic efficiency of Spirulina decreased from 8.72 to 2.002 due to cultivation in PCTE media. The maximum photosynthetic rate h–1 was slightly higher in ZMC as compared to PCTE media. The model parameter values were lower for Spirulina in PCTE than those in ZMC. Spirulina’s cell density was lower in PCTE compared to ZMC, as the doubling time was increased from 9.97 h–1 to 31.47 h–1. Moreover, the optimum pH for growth was also shifted from 9.5 to 10.5. The higher dose of PCTE (Cl– > 2.96 × 103 mg L–1) restricted cell growth. Adding Cr(III) in ZMC has a higher impact on cell growth than Cr(VI). The model parameters with Cr(III) and Cr(VI) also showed a decrease in values except rRc and β have higher values for Cr(VI) as compared to Cr(III) added ZMC due to the non-interaction of Cr(VI) with algae. The model-predicted cell growth rates closely align with experimental results, with deviations within an ±7% margin. The addition of heavy metals to ZMC disrupts nutrient interactions and transport mechanisms during Spirulina cell growth
H-Glass Supported Hybrid Gold Nano-Islands for Visible-Light-Driven Hydrogen Evolution
No full textFlat panel reactors, coated with photocatalytic materials, offer a sustainable approach for the commercial production of hydrogen (H2) with zero carbon footprint. Despite this, achieving high solar-to-hydrogen (STH) conversion efficiency with these reactors is still a significant challenge due to the low utilization efficiency of solar light and rapid charge recombination. Herein, hybrid gold nano-islands (HGNIs) are developed on transparent glass support to improve the STH efficiency. Plasmonic HGNIs are grown on an in-house developed active glass sheet composed of sodium aluminum phosphosilicate oxide glass (H-glass) using the thermal dewetting method at 550 °C under an ambient atmosphere. HGNIs with various oxidation states (Au0, Au+, and Au−) and multiple interfaces are obtained due to the diffusion of the elements from the glass structure, which also facilitates the lifetime of the hot electron to be ≈2.94 ps. H-glass-supported HGNIs demonstrate significant STH conversion efficiency of 0.6%, without any sacrificial agents, via water dissociation. This study unveils the specific role of H-glass-supported HGNIs in facilitating light-driven chemical conversions, offering new avenues for the development of high-performance photocatalysts in various chemical conversion reactions for large-scale commercial applications
Novel Eu<SUP>3+</SUP> doped mixed alkaline-earth zinc silico-aluminate glass for white-light-emitting diode, fingerprint, and security ink application
No full textIn this work, novel calcium strontium magnesium zinc silico-aluminate (CSrMZSAEux) glasses doped with varied concentrations of Eu2O3 (0.5, 1.0, 1.5, 2, 3, 4 and 5 mol%) were synthesized by an open-air melt quenching technique. The Raman and FTIR studies revealed that Eu3+ ions connected to both AlO4 and SiO4 units through non-bridging oxygen. The decrease in thermal stability from 158 to 141 degrees C with the gradual inclusion of Eu2O3 ions is showing modifier role of Eu3+ ions. The intense emission spectra (D-5(0) -> F-7(i) = (0-4) transitions) measured under 395 nm excitation wavelength, showed no concentration quenching within the studied dopant ions concentration. The high Judd-Ofelt parameter (Omega(2) = 5.06 to 6.31 x 10(-20) cm(2)) and red-to-orange emission intensity ratio (R = 3.627-4.102) have revealed the covalent nature of Eu-ligand bond and high color richness, respectively. Among all prepared glasses, the CSrMZSAEu5.0 glass showed high color purity (98.9%), correlated color temperature (<1000K), highest emission intensity and reasonable lifetime value (1387 +/- 16 mu s). Further, the temperature-dependent photoluminescence demonstrated that the CSrMZSAEu5.0 glass has good emission thermal stability (similar to 66% at 150 degrees C) with a high activation energy of 0.258 eV. Hence, the CSrMZSAEu5.0 glass can be used as red component for white-light-emitting diode, and red-light applications. Furthermore, the CSrMZSAEu5.0 glass composition is observed to be suitable for latent fingerprint and security ink applications
Effect of SrTiO3 incorporation in Mg matrix: Microstructure, mechanical, corrosion and in vitro bioactivity study
No full textIn the present study, magnesium-strontium titanate (Mg-SrTiO3) composites were prepared using powder metallurgy route. The physical, mechanical, and electrochemical properties of pure Mg were compared with those of Mg-SrTiO3 composites with varying SrTiO3 concentrations (0, 1 and 5 wt%). X-ray diffraction (XRD) results showed the SrTiO3 and Mg peaks in the composites. Scanning electron microscopy (SEM) of the composite revealed the uniform distribution of reinforcement in the Mg matrix. An electrochemical corrosion study showed that the Mg-SrTiO3 composite has more positive ECORR than pure Mg. The lowest corrosion rate was observed in the Mg-1 %SrTiO3 composite. An in vitro biocompatibility and antimicrobial study revealed that Mg-SrTiO3 composites are non-toxic and have mild antibacterial property
Thermal, structural, and conductivity properties of As14Sb26S(60-x)(AgI) chalcogenide glasses
No full textThe present work describes the preparation of a new series of chalcogenide glasses in an As14Sb26S(60-x) (AgI)(x) system intending to explore its thermal, structural, optical, mechanical, and electrical properties. The differential scanning calorimetry results of the studied glasses show the sharp decrease in glass transition temperature (T-g) with the successive incremental inclusion of AgI in the composition, implying the structural changes in the glass network. A thorough Raman analysis corroborates the occurrence of changes in the glass network due to the formation of AsI3 units and Ag-S-As bonds with increasing AgI content. Also, structural changes can be reflected with the change in the optical bandgap (E-g) that was calculated using Tauc equations where it was found that E-g is in harmony with the observed structural variations of glasses. The studied glasses possess a transmittance window (similar to 0.68-12 mu m) with transmittance above 60% in the mid-infrared region. These structural changes are closely related to the significant enhancement of conductivity of the present glasses from 10(-8) to 10(-6) S/cm at 373 K with a decrease in activation energies. Impedance spectra for the glass with highest AgI revealed the presence of two different relaxation processes. AC conductivity data followed an Arrhenius behavior as well as Jonscher's power law. The present work provides insights into glass network modifications due to silver iodide inclusion and its role in the enhancement of conductivity
Laser directed energy deposited Ti-48Al-2Cr-2Nb alloy: An investigation of high temperature oxidation behavior
No full textThis study investigates high-temperature oxidation behavior and kinetics of Laser Directed Energy Deposited (LDED) Ti-48Al-2Cr-2Nb (Ti-48-2-2) alloy at 750 degrees C, 850 degrees C, and 950 degrees C, for 30, 60 and 100 h. Results reveal that the oxide-scale consists of alternating bands of TiO2 and Al2O3 and its stability is strongly dependent on the oxidation temperature and duration. At 850 degrees C and 950 degrees C, the oxide-scale delaminated following 100-h exposure. LDED Ti-48-2-2 exhibited an oxidation rate constant of 0.984 mg(2) cm(-4) h(-1) at 850 degrees C (100 h) and 2.09 mg(2) cm(-4) h(-1) at 950 degrees C (100 h), and an activation energy of 83.7 kJ mol(-1) (850 degrees-950 degrees C). LDED Ti-48-2-2 exhibited poor oxidation resistance compared to conventionally processed Y-TiAl alloys. This can be attributed to the absence of N-rich layer and the typical nano-scale alpha(2)/gamma banded lamellar microstructure observed in other processing routes. Post-process heat treatments can be utilized to obtain the desired microstructural features
Cobalt containing antimicrobial bioactive glass coated urinary catheter towards management of catheter associated urinary tract infection (CAUTI): Significant in vitro characterization
No full textCatheter associated urinary tract infections (CAUTI) contributes to about 75 % of nosocomial urinary tract infections (UTI) and the risk potential is further escalated upon prolonged usage of the urinary catheter. Additionally, there is an increased risk for bloodstream infection from urinary source resulting in neutropenia and plethora of renal diseases. Over the past decades, numerous antibiotics/antimicrobial agents have been surface functionalized on catheter tubes but none proved effective owing to biofilm's tolerance. Further, in case of the indwelling urinary catheters, a thin fibrous capsule develops around the catheter, with no adhesion of the epithelial tissue. Additionally, recent reports of Co based bioactive glass exhibited potent antimicrobial action on both E. coli, P. aeruginosa (gram negative) and Candida albicans (fungus) which are primary causative organisms for CAUTI. In view of the above, we propose to fabricate a Co containing antimicrobial mesoporous bioactive glass (MBGCo) coated indwelling urinary catheter tubing, followed by its in vitro material (XRD, TG-DSC, FTIR, FESEM, BET and water contact angle determination), in-vitro bioactivity study and biological characterization (in-vitro cell cytotoxicity, antibacterial, antifungal studies, initial bacterial adhesion study etc.) of MBGCo coated urinary catheter tubing, along with antimicrobial studies and optimization of the same to obtain a preliminary prototype that is expected to address the issues of the existing urinary catheters
An Advanced Fabrication Method for Yb3+-Doped Optical Fibers Featuring Alpo4 Core Glass
No full textYtterbium (Yb)-doped fibers using aluminophosphosilicate (Yb-APS) host glass offer significant advantages over conventional aluminosilicate (Yb-AS) fibers, such as strong photodarkening resistance, higher RE-ion solubility and lower Numerical Aperture (NA), making them ideal for high-power laser applications. However, achieving optimal performance in Yb-APS fiber fabrication poses various challenges, including maintaining a precise Al3+/P5+ ratio (1:1), minimizing the central dip in the refractive index profile (RIP), ensuring proper dopant distribution, and reducing background loss. We introduce a new fabrication method for Yb-APS fiber to address these challenges. This approach entails first synthesizing amorphous Yb³⁺: AlPO4 particles, then incorporating them into the fiber core using a hybrid technique that merges Vapor Phase Delivery (VPD) with solution doping (SD). We extensively utilized various materials and optical characterizations, including XRD, FTIR, Raman spectroscopy, FESEM, and XPS, to fine-tune the composition of Yb³⁺: AlPO4. The optical characterization of the developed preform sample, including absorption, emission, and luminescent lifetime measurements, was conducted to assess the fabrication technique's suitability. The results confirmed the successful incorporation of Yb-ions into the preform core, with peaks consistent with reported values. The fiber's attenuation loss was measured, showing approximately 10 dB/km at 1200 nm. This indicates that the particles dissolved smoothly during preform and fiber processing, resulting in minimal scattering loss in the fiber core. The developed fiber demonstrated NA of 0.1, uniform RIP along the preform length with significant reduction of the central dip formation and improved spectral performance (∼1.7X broader bandwidth) compared with an equivalent Yb-AS fiber. These findings suggest the Yb-APS fiber's overall effectiveness and structural robustness, highlighting the potential of the proposed fabrication method for high-power fiber laser applications
Effect of Compositional Modification of Bioactive Glasses Towards High Temperature Processability and In Vitro Biological Properties
No full textThis study aimed to develop bioactive glasses with enhanced thermal stability and biocompatibility for bone tissue engineering applications. By strategically incorporating boron oxide (B2O3) and adjusting the CaO/Na2O ratio, glasses were successfully formulated with superior thermal processability, antibacterial properties, and biomineralization capabilities. A comprehensive composition-structure-property relationship was established, revealing that B2O3 addition strengthens the glass network, leading to improved thermal stability (<150 °C) while retaining fast bioactivity (1 day). Additionally, increasing CaO content while maintaining an optimal SiO2/B2O3 ratio resulted in enhanced mechanical properties and a closer match (α50-300 = 8.5 × 10-6 /°C) to the thermal expansion coefficient of titanium-based implants. Moreover, these glasses with modified compositions demonstrated exceptional in vitro biological performance, promoting cell growth and inhibiting antibacterial properties. The optimized glass compositions were further utilized for fabrication of amorphous tissue engineering constructs such as scaffold and coating highlighting the potential of such compositions for tissue engineering applications. Crystallization kinetics studies guided the development of amorphous bioactive glass scaffolds through controlled sintering processes. Furthermore, a novel bioactive glass coating was successfully fabricated on titanium-based implants. This coating exhibited superior biocompatibility and antibacterial properties compared to conventional bioactive glass (45S5) coatings. Overall, this study offers valuable insights for the design and fabrication of tailored bioactive glass-based materials while also proposing optimized formulations for bioactive glass-based scaffold and coating for bone tissue engineering applications
Multifaceted Biomedical Applications of Bismuth Oxide-Doped Bioactive Glass: Synthesis Challenges, Characterization and Potential Clinical Implications
No full textHerewith, the present work reports a facile synthesis method of Bi2O3 doped 70 SiO2.30CaO binary bioactive glass system termed as modified Bi-BG (acronymed as mBi-BG) that indicates successful incorporation of Bi3+ into the silicate glassy network, on prior complex formation of the precursor bismuth nitrate salt with acetyl acetone to address the rapid decomposition rate of precursor bismuth nitrate. The binary bioactive glass composition as above mentioned (70 SiO2.30CaO) is named as BG/Control. The synthesis methodology addresses inherent challenges encountered in traditional sol-gel derived bismuth oxide incorporated bioactive glass (Bi-BG) synthesis wherein yellow coloured bismuth oxide gets separated from the glassy network as confirmed by XRD phase analysis. Next, mBi-BG (modified Bi-BG) was synthesized via modifying the sol gel method by introducing a chelating agent acetyl acetone to stabilize the precursor Bi (NO3)3 salt, and was characterized using XRD, FTIR, FESEM-EDX. TG-DSC and BET isotherm. In vitro bioactivity studies illustrate the formation of hydroxyapatite crystals on mBi-BG surface indicating its potential for bone repair and regeneration. Additionally, mBi-BG exhibits significant effect against Staphylococcus aureus (gram-positive) bacterial strain, highlighting its utility in preventing bacterial infections at surgical sites. Radiographic imaging of mBi-BG reveals excellent radiopacity comparable to human bone, rendering it suitable for image-guided surgeries and fluoroscopic procedures. In summary, mBi-BG emerges as a versatile biomaterial with enhanced bioactivity, antibacterial efficacy and radiopacity, thereby offering novel avenues in medical treatment modalities and patient care