Transparent polymeric materials such as poly(methyl methacrylate) (PMMA), polycarbonate (PC), and polyethylene terephthalate (PET) are widely used as glass alternatives in algal bioreactors, where optical clarity and mechanical stability are crucial. However, their long-term use is limited by surface degradation processes. Photodegradation, hydrolysis, and biofilm accumulation can reduce light transmission in the 400–700 nm range essential for photosynthesis. This study examined the aging of PMMA, PC, and PET under bioreactor conditions. Samples were exposed for 70 days to illumination, culture medium, and aquatic environments. Changes in their optical transmittance, surface roughness, and wettability were analyzed. All polymers exhibited measurable surface degradation, characterized by an average 15% loss in transparency, significant increases in surface roughness, and reduced contact angles. PMMA demonstrated the highest optical stability, maintaining strong transmission in key blue and red spectral regions, while PET performed the worst, showing low initial clarity and the steepest decline. The most severe surface degradation occurred in areas exposed to the receding liquid interface, highlighting the need for targeted cleaning and/or a reduction in the size of the liquid–vapor transition zone. Overall, the results identify PMMA and recycled PMMA (PMMA_R) as durable, cost-effective materials for transparent bioreactor walls.

This work presents borosilicate glasses co-doped with PbS quantum dots and Er3+ ions for broadband NIR luminescence. The heat- treatment increased the absorbance of glass in the visible range and shits absorption edge towards longer wavelengths. Glass co-doped with PbS/Er3+ after heat-treatment at 490°C showed broadband luminescence in 1-1.6 µm range under pumping at the wavelength of 980 nm. In the case of pumping at the wavelength of 808 nm, the obtained band was lower due to non-radiative processes and finally, lower intensity of Er3+ ions luminescence. Full Text: PDF References M.S. Dhlamini, G.H. Mhlongo, H.C. Swart, K.T. Hillie, "Energy transfer between doubly doped Er3+, Tm3+and Ho3+ rare earth ions in SiO2 nanoparticles", J. Lumin., 131(4), 790 (2011). CrossRef Z. Gao et al., "Selective doping of Ni2+ in highly transparent glass-ceramics containing nano-spinels ZnGa2O4 and Zn1+x Ga2−2x Ge x O4 for broadband near-infrared fiber amplifiers", Sci. Rep. 7(1), 1783 (2017). CrossRef M.A. Hughes, T. Suzuki, Y. Ohishi, "Spectroscopy of bismuth-doped lead–aluminum–germanate glass and yttrium–aluminum–silicate glass", J. Non-Cryst. Solids, 356(44–49), 2302 (2010). CrossRef X. Huang, Z. Peng, Q. Guo, X. Song, J. Qiu, G. Dong, "Energy transfer process and temperature‐dependent photoluminescence of PbS quantum dot‐doped glasses", J. Am. Ceram. Soc., 102(6), 3391 (2019). CrossRef N. Shasmal, W.J.G.J. Faria, A.S.S. de Camargo, A.C.M. Rodrigues, "Significant enhancement in Eu3+/Eu2+ emissions intensity by CdS quantum dots, in chloroborosilicate glasses", J. Lumin., 243, 118623 (2022). CrossRef Y. Yu, "Ultra-stable Eu3+-doped CsPbCl2Br1 perovskite quantum dots glass for optical temperature sensing", J. Rare Earths, 39(12), 1497 (2021). CrossRef E.O. Serqueira, N.O. Dantas, "Determination of the energy transfer section between CdS semiconductor quantum dots and Nd3+ ions", Opt. Mater., 90,252 (2019). CrossRef M.A. Kim, Y.K. Kwon, C. Liu, J. Heo, "Lead sulfide quantum dots in glasses containing rare-earth ions", J. Non-Cryst. Solids, 383, 173 (2014). CrossRef W.J. Park, C. Liu, J. Heo, "Direct Imaging of the Distribution of Nd3+ Ions in Glasses Containing PbS Quantum Dots", J. Am. Ceram. Soc., 98(7), 2074 (2015). CrossRef W. Wang et al., "PbS quantum dots and BaF2:Tm3+ nanocrystals co-doped glass for ultra-broadband near-infrared emission [Invited]", Chin. Opt. Lett., 20(2), 021603(2021). CrossRef W. Wang, Y. Xiao, B. Zhou, S. Xu, Q. Zhang, "Quantum-dots-precipitated rare-earth-doped glass for ultra-broadband mid-infrared emissions", J. Am. Ceram. Soc., 102(4), 1560 (2019). CrossRef D. Chen et al., "Broadband Optical Amplification of PbS Quantum-Dot-Doped Glass Fibers", Adv. Photonics Res., 3(9), 2200097 (2022). CrossRef C. Cheng, F. Wang, X. Cheng, "PbSe quantum-dot-doped broadband fiber amplifier based on sodium-aluminum-borosilicate-silicate glass", Opt. Laser Technol., 122, 105812 (2020). CrossRef T. Zha, P. Zhang, X, Jin, Y. Long, T. Huang, H. Jia, Z. Fang, B.O. Guan, "Glass Ceramic Fibers Containing PbS Quantum Dots for Fluorescent Temperature Sensing", Nanomaterials 14(10), 882 (2024). CrossRef N.A. Nabilah Razali et al., "The Physical and Optical Studies of Erbium Doped Borosilicate Glass", J. Phys. Conf. Ser., 1083(1), 012004 (2018). CrossRef

The article presents the investigation of the AC dielectric properties of optical glass rods co-doped with Ag nanoparticles. The samples presented a molar composition of 20Sb2O3–30GeO2–(45 – x )H3BO3–5Al2O3–xAg and differed with Ag concentration x in the range of 0.1 mol.%-0.6 mol.% as well as geometric dimensions. The rods have been prepared by the standard melt-quenching technique. An impedance spectroscopy in the measurement frequency range of 4 Hz–8 MHz at room temperature was used to determine the dielectric properties of rods. The paper shows frequency characteristics for impedance, phase shift angle, resistance, conductivity, dissipation factor, and both components of permittivity. The samples demonstrate high resistance (4.4 x 106 < R < 2.0 x 1011 Ω) and mostly negative phase shift angle (0 < θ ≤ –90°), which indicates the purely dielectric nature of the materials and their capacitive character. Introducing Ag NPs into the rod’s structure causes growth in the impedance of about 40–120%, amplifies the real part of the per-mittivity over fivefold, and increases the electrical conductivity from two to 4.5 times, de-pending on frequency f. Resistance, conductivity, dissipation factor, and imaginary part of permittivity demonstrate two-step saddle-shape dependencies that reflect dielectric and conduction processes between non- or partly oxidized or fully oxidized Ag nanoparticles separated by a glass matrix. The saddle points are different for low and high frequency regions, the values of which are next to 500 Hz and 5 x 105 Hz, respectively, referring to two relaxation times in the interphase polarization process. Hopping conductivity has been proposed as the charge transfer mechanism in nanocomposite rods.