Rigid Glass Research Articles

The influence of polyacrylamide gel substrate elasticity on primary cultures of rat retinal ganglion cells

In vitro primary cell culture models of retinal ganglion cells (RGC) are widely used to study pathomechanisms of diseases such as glaucoma. The biomechanic interaction with the culture substrate is known to influence core cellular functions. RGC cultures, however, are usually grown on rigid plastic or glass substrates. We hypothesized that soft polyacrylamide gel substrates may alter survival and neurite outgrowth of primary cultured RGC.Primary retinal cultures from postnatal (day 1-6) Wistar rats were grown on glass coverslips or polyacrylamide (PA) gel substrate with different Young’s elastic moduli (0.75, 10 or 30 kPa). Substrates were coated with Poly-l-lysine and / or laminin. RGC were immunostained with anti-beta-III-tubulin. Total neurite length, growth cone morphology, RGC density, mitochondrial morphology and transport as well as pro-survival pathways (Erk1/2, Akt, CREB) were assessed.PA gel substrates of E = 10 kPa significantly increased the total neurite length by factor 1.5 compared to glass (p = 0.02). The growth cone area was significantly larger by factor 5.3 on 30 kPa gels (p = 0.01). The presence of a substrate coating was more important for neurite outgrowth and RGC survival on PA gels (poly-l-lysine > laminin) than on glass. Neither mitochondrial morphology and motility nor the activation of pro-survival pathways significantly differed between the four substrates.PA gel substrates significantly enhanced RGC neurite outgrowth. The signaling cascades mediating this effect remain to be determined.

Native mechano-regulative matrix properties stabilize alternans dynamics and reduce spiral wave stabilization in cardiac tissue.

The stability of wave conduction in the heart is strongly related to the proper interplay between the electrophysiological activation and mechanical contraction of myocytes and extracellular matrix (ECM) properties. In this study, we statistically compare bioengineered cardiac tissues cultured on soft hydrogels ( kPa) and rigid glass substrates by focusing on the critical threshold of alternans, network-physiological tissue properties, and the formation of stable spiral waves that manifest after wave breakups. For the classification of wave dynamics, we use an improved signal oversampling technique and introduce simple probability maps to identify and visualize spatially concordant and discordant alternans as V- and X-shaped probability distributions. We found that cardiac tissues cultured on ECM-mimicking soft hydrogels show a lower variability of the calcium transient durations among cells in the tissue. This lowers the likelihood of forming stable spiral waves because of the larger dynamical range that tissues can be stably entrained with to form alternans and larger spatial spiral tip movement that increases the chance of self-termination on the tissue boundary. Conclusively, we show that a dysfunction in the excitation-contraction coupling dynamics facilitates life-threatening arrhythmic states such as spiral waves and, thus, highlights the importance of the network-physiological interplay between contractile myocytes and the ECM.

Construction of Vine-Inspired Antimicrobial Filter with Multiscale 3D Nanonetwork for High-Efficiency Air Filtration.

Enhancing the antimicrobial activity of high-efficiency particulate air (HEPA) filters while maintaining filtration efficiency and pressure drop is currently an urgent issue for preventing the spread of pathogenic microorganisms. Herein, inspired by vines which can enwind fences to fix as well as decorate them, a flexible antimicrobial chitin nanofiber (ChNF@CuOx) was fabricated and loaded onto the rigid glass fiber (GF) skeleton of a HEPA filter. Through the physical interaction, ChNF@CuOx was spontaneously enwound on GF, and ChNF@CuOx itself interweaved to form a new nanonetwork between the GF skeleton. The obtained antimicrobial air filter (ChNF@CuOx/GF) with a unique nanonetwork increased the filtration efficiency of the HEPA filter. Meanwhile, it possessed excellent inactivation ability against Staphylococcus aureus, Escherichia coli, and Candida albicans due to the urchin-like in situ grown CuOx on the ChNF. In particular, the oxygen vacancies generated unexpectedly in CuOx enabled it to produce reactive oxygen species. After eight cycles of antimicrobial assays, the antimicrobial rates of bacteria were higher than 99.5%, and those of fungi were greater than 98.3%. The successful synthesis of antimicrobial fibers and the construction of multidimensional nanoscale structures through a simple postprocessing method provide a new design mentality for antimicrobial functionalization for HEPA filters.

Is Ortho-Terphenyl a Rigid Glass Former?

Ortho-terphenyl (OTP) has long been used as a model system to study the glass transition due to its apparent simplicity and a widespread assumption that it is a rigid molecule. Here, we employ terahertz time-domain spectroscopy and low-frequency Raman spectroscopy to investigate the rigidity of OTP by direct observation of the low-frequency vibrational dynamics. These terahertz phonons involve complex large-amplitude atomic motions where intramolecular and intermolecular displacements are often mixed. Comparison of experimental results with density functional theory and ab initio molecular dynamics simulations shows that the assumption of rigidity neglects important implications for the glass transition and must be revisited. These results highlight the significance of terahertz modes on elasticity, which will be even more critical in more complex systems such as biomolecules.

Influence of Surface Chemical and Topographical Properties on Morphology, Wettability and Surface Coverage of Inkjet-Printed Graphene-Based Materials.

The inkjet printing of water-based graphene and graphene oxide inks on five substrates, two rigid (silicon and glass) and three flexible (cellulose, indium tin oxide-coated polyethylene terephthalate (ITO-PET) and ceramic coated paper (PEL paper)), is reported in this work. The physical properties of the inks, the chemical/topographical properties of selected substrates, and the inkjet printing (IJP) of the graphene-based materials, including the optimisation of the printing parameters together with the morphological characterisation of the printed layers, are investigated and described in this article. Furthermore, the impact of both the chemical and topographical properties of the substrates and the physical properties of graphene-based inks on the morphology, wettability and surface coverage of the inkjet-printed graphene patterns is studied and discussed in detail.

The Influence of the Mechanical Compliance of a Substrate on the Morphology of Nanoporous Gold Thin Films.

Nanoporous gold (np-Au) has found its use in applications ranging from catalysis to biosensing, where pore morphology plays a critical role in performance. While the morphology evolution of bulk np-Au has been widely studied, knowledge about its thin-film form is limited. This work hypothesizes that the mechanical compliance of the thin film substrate can play a critical role in the morphology evolution. Via experimental and finite-element-analysis approaches, we investigate the morphological variation in np-Au thin films deposited on compliant silicone (PDMS) substrates of a range of thicknesses anchored on rigid glass supports and compare those to the morphology of np-Au deposited on glass. More macroscopic (10 s to 100 s of microns) cracks and discrete islands form in the np-Au films on PDMS compared to on glass. Conversely, uniformly distributed microscopic (100 s of nanometers) cracks form in greater numbers in the np-Au films on glass than those on PDMS, with the cracks located within the discrete islands. The np-Au films on glass also show larger ligament and pore sizes, possibly due to higher residual stresses compared to the np-Au/PDMS films. The effective elastic modulus of the substrate layers decreases with increasing PDMS thickness, resulting in secondary np-Au morphology effects, including a reduction in macroscopic crack-to-crack distance, an increase in microscopic crack coverage, and a widening of the microscopic cracks. However, changes in the ligament/pore widths with PDMS thickness are negligible, allowing for independent optimization for cracking. We expect these results to inform the integration of functional np-Au films on compliant substrates into emerging applications, including flexible electronics.

Progress in 3D printing of recycled PET

Filaments from blends of post-industrial, low-quality recycled poly(ethylene terephthalate) (RPET) and ethylene-butyl-acrylate-glycidyl-methacrylate (EBA-GMA) were extruded with different EBA-GMA contents, then specimens were 3D-printed by fused filament fabrication technology. It has been demonstrated that, when 0–90° layer order is applied, at 15 wt% EBA-GMA content the unnotched impact strength increases by two and a half times and the notched impact strength by nine times compared to samples printed from elastomer-free RPET. DSC and DMA measurements proved that EBA-GMA reactively bonds to PET molecules, which is indicated by the increment of rigid amorphous phase and glass transition temperature and the reduction of crystallinity. The co-polymer molecules formed in-situ during compounding create a Toughening Enhancer Interphase (TEI), which also remains after 3D printing and effectively enhances impact strength. The strain at break and tensile strength of the filaments are substantially higher than that of 3D-printed specimens due to the increasing shrinkage and the resulting increased porosity of the printed specimens with higher EBA-GMA content. However, the Young-modulus values are quite similar. The flexural strength of the 3D-printed specimens reaches 40–60% of the values of injection moulded samples. The proposed method enables the production of parts with arbitrary geometry and balanced mechanical properties from RPET, which may substitute acrylonitrile butadiene styrene.

Viscosity of Mono‐ and Polydisperse Mixtures of Photopolymer and Rigid Spheres for Manufacturing of Engineered Composite Materials Using Vat Photopolymerization

Vat photopolymerization (VP) additive manufacturing involves selectively curing low‐viscosity photopolymers via exposure to ultraviolet light in a layer‐wise fashion. Dispersing filler materials in the photopolymer enables tailored end‐use properties, but also increases the viscosity and the timescale associated with interparticle network structural recovery postshear. These rheological properties influence self‐leveling and recoating of the liquid photopolymer mixture during VP. Herein, viscosity of photopolymer and rigid spherical glass microparticles (filler) is experimentally determined as a function of filler fraction, filler size distribution (mono‐ and polydisperse), shear rate, and temperature, which are important VP process parameters. Employing existing viscosity models for mono‐ and polydisperse polymer mixtures demonstrates that particle–particle interactions and the formation of nonspherical clusters of particles strongly affect the viscosity of both monodisperse and polydisperse mixtures with particle volume fractions > 0.05 due to agglomeration/deagglomeration of clusters at elevated shear rates. Consequently, unmodified viscosity models, which assume uniformly dispersed, rigid, spherical particles, are applicable only for mixtures with particle volume fractions < 0.05. It is shown that modifying model parameters such as the fluidity limit and intrinsic viscosity, which explicitly account for nonspherical clusters of particles, improves agreement between viscosity models and experiments, in particular when using a fractal approach.

Density Functional Theory Approach to Interpret Elastowetting of Hydrogels.

Sessile hydrogel drops on rigid surfaces exhibit a wetting/contact morphology intermediate between liquid drops and glass spheres. Using density functional theory, we reveal the contact forces acting between a hydrogel and a rigid glass surface. We show that while transitioning from liquid-like to solid-like hydrogels, there exists a critical hydrogel elasticity that enables a switch from attractive-to-repulsive interaction with the underlying rigid glass surface. Our theoretical model is validated by experimental observations of sessile polyacrylamide hydrogels of varying elasticity on glass surfaces. Further, the proposed model successfully approaches Young's law in the pure liquid limit and work of adhesion in the glassy limit. Lastly, we show a modified contact angle relation, taking into account the hydrogel elasticity to explain the features of a distinct hydrogel foot.

Dual-meniscus-assisted roller-coating for scalable and patterned perovskite solar cells

Scaling up the fabrication process for perovskite solar cells has emerged as a prominent research focus in the field of perovskite photovoltaics. Current methods for preparing large-scale perovskite solar cells often struggle to meet the simultaneous requirements of continuous production, high compatibility, and low commissioning costs necessary for industrial-scale manufacturing. Here, the roller coating method is demonstrated to realize the preparation of large-scaled and uniform perovskite films with customized patterning through a facile and stable “touch-and-roll” motion. The unique fabric-based roller and “dual-meniscus” structure guarantee accurate control of ink flow and film thickness, thereby realizing the reproducible preparation on different substrates ranging from rigid glass to flexibe polymer film. The method yielded PSCs with peak efficiencies of 14.11% (0.16 cm2) and 10.61% (1 cm2). This roller coating method exhibits a promising new avenue for advancing the scale and commercial development of perovskite photovoltaics.

Bio-Inspired Organic Synaptor with In Situ Ion-Doped Ultrathin Polyelectrolyte Containing Acetylcholine-Like Cation.

An ion-based synaptic transistor (synaptor) is designed to emulate a biological synapse using controlled ion movements. However, developing a solid-state electrolyte that can facilitate ion movement while achieving large-scale integration remains challenging. Here, a bio-inspired organic synaptor (BioSyn) with an in situ ion-doped polyelectrolyte (i-IDOPE) is demonstrated. At the molecular scale, a polyelectrolyte containing the tert-amine cation, inspired by the neurotransmitter acetylcholine is synthesized using initiated chemical vapor deposition (iCVD) with in situ doping, a one-step vapor-phase deposition used to fabricate solid-state electrolytes. This method results in an ultrathin, but highly uniform and conformal solid-state electrolyte layer compatible with large-scale integration, a form that is not previously attainable. At a synapse scale, synapse functionality is replicated, including short-term and long-term synaptic plasticity (STSP and LTSP), along with a transformation from STSP to LTSP regulated by pre-synaptic voltage spikes. On a system scale, a reflex in a peripheral nervous system is mimicked by mounting the BioSyns on various substrates such as rigid glass, flexible polyethylene naphthalate, and stretchable poly(styrene-ethylene-butylene-styrene) for a decentralized processing unit. Finally, a classification accuracy of 90.6% is achieved through semi-empirical simulations of MNIST pattern recognition, incorporating the measured LTSP characteristics from the BioSyns.

Corneal Rigid Gas Permeable Contact Lens in Corneal Scarring: a Case Report

Introduction : Corneal scarring is part of corneal wound healing response to injury, surgery, or infection to the cornea. Corneal scarring causes significant visual reduction. This case report highlights visual acuity (VA) improvement in patient with corneal scarring following rigid glass permeable contact lens (RGP-CL)
 Case Illustration : A 25 year-old male presented blurry vision in right eye (RE) due to trauma. His VA was 3/60 on RE and 6/6 on left eye (LE). The best corrected visual acuity (BCVA) of RE was 6/45 (S-1.25 C-5.00 X 180°). Slit lamp examination of RE showed corneal scarring in central area and deep neovascularization. Keratometry readings obtained 39.50D (8.48mm) at 170 degree and vertical curvature of 44.00D (7.68mm) at 80 degree, with markedly irregular mires of RE. A trial fitting was performed for RE by using tisilfocon A lens with base curve of 8.30 mm, power S-4.00D and diameter 9.20 mm. The over-refraction with trial lens obtained a total refractive error of S-6.00 with cylindrical correction neutralize with RGP. The achieved BCVA by over-refraction was 6/45 with comfortable fit.
 Discussion : Rigid permeable lens (RGP) is an option in dealing with irregular astigmatism due to corneal scarring. The RGP fitting works best especially when the corneal scarring is not in the center of visual pathway. Rigid lens works by providing tear-lens power and creating smooth surface to neutralize the irregular cornea. Good RGP-CL fitting could help patient with corneal carring gain better VA.
 Conclusion : Good rigid permeable contact lens fitting could help patients with corneal scarring gain better VA.

Innovative strategy for controlling resonant frequencies of syntactic polymer foams regulating by hollow microspheres

This study aims to precisely control the resonant frequency of synthetic composite foam materials with fixed dimensions. By incorporating rigid hollow glass microspheres XLD3000(XLD) and flexible hollow polymer microspheres MFL-81GCA(MFL) into the base resin (EP), we prepared synthetic composite foams containing different volume fractions of hollow microspheres (EP-XLD and EP-MFL). We conducted tests and analyses on the density, mechanical properties, resonant frequency, and microstructure of the EP-XLD and EP-MFL systems. Results indicate that as the volume fraction of hollow microspheres increases, the flexural specific modulus of the EP-XLD and EP-MFL systems, respectively, exhibits a linear increase and decrease, and the resonant frequency shifts linearly towards higher and lower frequencies. This trend aligns with theoretical predictions, affirming that the material’s resonant frequency is closely related to its flexural modulus. This research not only deepens the understanding of the control mechanisms for the resonant frequency of synthetic composite foams but also proposes an innovative material design strategy with broad application potential, particularly in the fields of acoustics, damping, and structural materials, where it promises to significantly enhance material performance and meet specific engineering needs.

Substrate effects on structural and optoelectronic properties of quasi-2D perovskite films

This work presents a comprehensive investigation into the impact of different substrates—both rigid (glass and single-crystal silicon) and flexible (PEN and PDMS)—on the structural and optoelectronic behavior of quasi-2D perovskite films.

ZnSb Films on Flexible Substrates: Stability, Optical Bandgap, Electrical Properties, and Indium Doping

AbstractUndoped and In‐doped ZnSb thin films are deposited on rigid glass and flexible polyimide (Kapton) by physical vapor deposition. Detailed structural and chemical characterization is performed along with measurement of electrical and optical properties. These properties are very similar for films on glass and Kapton. Flexible ZnSb films show remarkable stability of electrical and optical properties, which are unchanged after 104 cycles of linear bending with surface strain 0.18%. Only severe flexing after this treatment (torsional bending with surface strain 1.7%) causes progressive degradation of conductivity over tens to hundreds of cycles. The ZnSb optical direct gap is determined to be 0.89 ± 0.05 eV. The optical direct gap of β Zn4Sb3 was 1.07 ± 0.05 eV. Other absorption features in the films, including smaller indirect gaps, are discussed.

Semi-quantitative graphene chemiresistor enzyme immunoassay for simple and sensitive antigen detection

Graphene is an ideal platform for sensing biomolecule charges due to its high electron/hole mobilities and 2D nature. However, when directly detecting biomolecules on graphene surfaces, it is important to consider their charge magnitude and the impact of Debye screening, which limits the detectable biomolecule types. Therefore, we propose a graphene chemiresistor enzyme immunoassay that allows for the detection of all protein types, regardless of charge or size. In this study, we immobilized antibodies on rigid glass surfaces rather than graphene surfaces to simplify the washing process and reduce noise caused by solution flow on graphene. As an example, we used influenza virus nucleoprotein as the antigen and urease as the enzyme. By measuring changes in graphene's electrical conductivity resulting from ammonium ions generated by enzymatic reactions, we confirmed antigen presence. The responsiveness of the graphene chemiresistor varied depending on antigen concentration, successfully detecting 100 pM antigens in this experiment. Our semi-quantitative method offers a simple and highly sensitive electrical detection of antigens.

The Caste of Campus Habitus: Caste and Gender Encounters of the First-generation Dalit Women Students in Indian Universities

This article critically examines the university academic spaces and the campus culture determined by a particular form of the dominant habitus which is, in effect, actively excluding the first-generation women students belonging to the marginalized sections of Indian society. As this dominant habitus is constantly reproduced on university campuses, with or without contentions, entering the academic spaces of Indian universities for first-generation Dalit women—who are deprived of both cultural and social capital—is invariably becoming a herculean task. Therefore, this article analyses the concealed forms of dominant campus habitus that structurally create a conducive environment for privileged students and a rigid glass ceiling for first-generation Dalit women students in their journey toward higher education. Notwithstanding the limitations associated with their social status of being first-generation learners, the formations of alternative cultural capital and resilience of the Dalit women students have been analysed from a feminist perspective, proving that one could overcome these social challenges through the acquired cultural capital. The analytical concepts and theoretical frameworks of this article have been developed based on empirical/ethnographic data collected from women research scholars at a prominent university in South India. The narratives were collected in the academic year 2020–2021 through in-depth interviews and focused group discussions.

Optimization of Oligomer Stamping Technique for Normally Closed Elastomeric Valves on Glass Substrate.

Microscale elastomeric valves are an integral part of many lab-on-chip applications. Normally closed valves require lower actuation pressures to form tight seals, making them ideal for portable devices. However, fabrication of normally closed valves is typically more difficult because the valve structure must be selectively bonded to its substrate. In this work, an oligomer stamping technique for selective bonding of normally closed valves is optimized for bonding of PDMS devices on glass substrates. Contact angle and blister bursting testing measurements are used to quantitatively characterize the oligomer stamping process for the first time, and recommendations are made for plasma treatment conditions, microstamping technique, and valve construction. Glass-PDMS devices are ideal for lab-on-chip systems that integrate electrodes on the rigid glass substrate. Here, integrated electrodes are used to assess valve performance, demonstrating electrical isolation in excess of 8 MΩ over the biologically relevant frequency range in the closed state. Further, electrical measurement is used to demonstrate that the valve design can operate under a pulsed actuation scheme, sealing to withstand fluid pressures in excess of 200 mbar.

The development of Au-titania photoanode composites toward semiflexible dye-sensitized solar cells

Considering the widespread use of windows in modern urban landscapes, converting these substrates into photovoltaic devices would remarkably impact modern energy generation. A flexible dye-sensitized solar cell (DSSC) architecture is preferred for such applications. A key component of the DSSC is the dye-sensitized photoanode. Herein, we examine different nanoparticle composites within the semiconductor anode formulation and their effect on device performance. Mesoporous titania particles (TiO2) modified with Au-nanoparticles (TiO2@AuNPs) were synthesized using precipitation strategies to assess the solvent effect on the particle size and the efficiency of the devices. The materials were then fully characterized through SEM, XRD, and DRS before and after thermal treatment. A paste prepared from the synthesized semiconductors was applied onto the substrate using the doctor blading technique. The use of high thermal treatment for glass substrates (HTT), low-temperature thermal treatment (LTT), and LTT combined with 2 h of UV curing (LTT_UV) was explored. In the case of ITO/PET (flexible substrate) only low temperature thermal treatment were used (LTT and LTT_UV). After characterization (XRD and DRS), the anodes were loaded using a metal-free dye. To complete the comparison, several groups of cells were characterized: considering solvent (EtOH and EtOH:H2O), thermal treatment (HTT, LTT, and LTT_UV), and semiconductor material (TiO2 and TiO2@AuNP). Rigid (glass anode-glass cathode) and semiflexible (flexible anode-glass cathode) DSSCs were obtained with efficiencies from 0.03% to 2.4%, with a substantial performance difference seen using different thermal treatments, and a mild to low effect on semiconductor composition and the used substrate.

Boosting Nd3+ emission in Nd/Al/Y co-doped silica glass by mid-range localized environmental manipulation

Improving the repetition frequency of high-energy lasers is vital to promote the development and application of high-energy lasers, and its key lies in finding the laser gain media with excellent thermal shock resistance and high emission cross-section. Rare-earth ion (RE3+)-doped silica glass, whose thermal shock parameter is 1.5 times higher than that of yttrium aluminum garnet (YAG) crystals, is expected to satisfy this criterion after enhancing the emission intensity of RE3+. Nevertheless, modulating the spectral properties of RE3+ in rigid silica glass networks poses a significant challenge. Herein, we propose a mid-range localized environmental manipulation approach, which dramatically changes the microscopic symmetry of RE3+ from amorphous to the desired crystal structures for emission enhancement. As a representative, Nd/Y/Al co-doped silica glasses were prepared and heat-treated for different durations to form different mid-range localized environments, which were demonstrated by transmission electron microscopy, electron paramagnetic resonance tests, and Judd-Ofelt theory analysis. The results show that Nd3+ enters the YAG structure in favor of its emission enhancement. After optimizing the mid-range local environment of Nd3+ to balance fluorescence enhancement with fluorescence quenching and Rayleigh scattering, the emission intensity increases by 300%. Our work suggests that the mid-range localized environmental manipulation approach is extremely promising for promoting the development of high-energy and high-repetition-rate lasers. Furthermore, this approach can be generalized to adjust the emission characteristics of other RE3+-doped glasses and fibers.