Poly Methyl Methacrylate Research Articles

Expression of osteopontin and osteocalcin in Osteoblast cells exposed to a combination of polymethylmethacrylate (PMMA) and hydroxyapatite (HAp): A prospective observational study.

The success of implant placement will depend on the ability of the implant material to integrate with the surrounding tissue. Polymethylmethacrylate (PMMA) has been used as an implant material, but it has several fallback properties in its interaction with bone tissue. The addition of hydroxyapatite (HAp) to PMMA is expected to produce reinforced bioceramic polymers with better mechanical and biological properties. The purpose of this study was to evaluate the expression of osteopontin and osteocalcin in cultured osteoblasts when exposed to two implant candidate materials: PMMA-HApGMP, derived from bovine bone and processed under Good Manufacturing Practice by a Tissue Bank, and PMMA-HApBBK, sourced from limestone (CaCO3) and processed by Balai Besar Keramik. Twenty-four fetal rat calvariae osteoblast cell cultures were randomly divided into 6 groups: 7- and 14-day control group, 7 and 14 days PMMA-HApGMP group, 7 and 14 days PMMA-HApBBK group. The expression of osteopontin and osteocalcin was seen by immunocytochemical examination. The results showed that the average expression of osteopontin and osteocalcin in the treatment group on the 7th and 14th days was higher than the control group. The expression of osteopontin and osteocalcin in the PMMA-HApGMP group increased significantly (P < .05) on day 14. The PMMA-HAp combination material can accelerate the process of osteoblast differentiation which is characterized by an increase in osteopontin and osteocalcin which are markers of bone formation. This will support in increasing osseointegration.

Borosilicate bioactive glass synergizing low-dose antibiotic loaded implants to combat bacteria through ATP disruption and oxidative stress to sequentially achieve osseointegration

Bone infection is a catastrophe in clinical orthopedics. Despite being the standard therapy for osteomyelitis, antibiotic-loaded polymethyl methacrylate (PMMA) cement has low efficiency against bacteria in biofilms. Furthermore, high-dose antibiotic-loaded implants carry risks of bacterial resistance, tissue toxicity, and impairment of local tissue healing. By incorporating borosilicate bioactive glass (BSG) into low-dose gentamicin sulfate (GS)-loaded PMMA cement, an intelligent strategy that synergistically eradicates bacteria and sequentially promotes osseointegration, was devised. Results showed that BSG did not compromises the handling properties of the cement, but actually endowed it with an ionic and alkaline microenvironment, thereby damaging the integrity of bacterial cell walls and membranes, inhibiting ATP synthesis by disrupting the respiratory chain in cell membranes and glycogen metabolism, and elevating reactive oxygen species (ROS) levels by weakening antioxidant components (peroxisomes and carotenoids). These antibacterial characteristics of BSG synergistically reinforced the effectiveness of GS, which was far below the actual clinical dosage, achieving efficient bacterial killing and biofilm clearance by binding to the 30S subunit of ribosomes. Furthermore, the released GS and the ionic and alkaline microenvironment from the implants fostered the osteogenic activity of hBMSCs in vitro and coordinately enhanced osseointegration in vivo. Collectively, this study underscores that BSG incorporation offers a promising strategy for reducing antibiotic dosage while simultaneously enhancing the antibacterial activity and osteogenesis of implants. This approach holds potential for resolving the conflict between bacterial resistance and bone infection.

CO2‐Responsive Copolymers for Membrane Applications, Synthesis, and Performance Evaluation

AbstractThe urgent need to mitigate climate change has spurred research into innovative carbon dioxide (CO2) capture materials. In this study, the design and synthesis of CO2‐responsive diblock copolymers, poly (N‐[3‐(dimethylamino)propyl]‐acrylamide)‐b‐poly(methyl methacrylate) (PDMAPAm‐b‐PMMA) are focused on via a two‐step reversible addition−fragmentation chain‐transfer (RAFT) polymerization as well as the application of the synthesized diblock copolymer as a membrane for CO2 capture. The resulting diblock copolymer possesses distinct blocks with varying properties. The poly (N‐[3‐(dimethylamino)propyl]‐acrylamide) (PDMAPAm) block provides CO2‐responsive behavior, while the poly(methyl methacrylate) (PMMA) block contributes to mechanical stability. The gas transport properties of the fabricated thin‐film composite membrane made of PDMAPAm‐b‐PMMA are measured. It is determined that the copolymer exhibits dual responsiveness towards CO2 and can be tailored for use in fabrication of membranes for direct air capture (DAC).

Reliable fabrication of 3D freestanding nanostructures via all dry stacking of incompatible photoresist

Three-dimensional (3D) free-standing nanostructures based on electron-beam lithography (EBL) have potential applications in many fields with extremely high patterning resolution and design flexibility with direct writing. In numerous EBL processes designed for the creation of 3D structures, the multilayer resist system is pivotal due to its adaptability in design. Nevertheless, the compatibility of solvents between different layers of resists often restricts the variety of feasible multilayer combinations. This paper introduces an innovative approach to address the bottleneck issue by presenting a novel concept of multilayer resist dry stacking, which is facilitated by a near-zero adhesion strategy. The poly(methyl methacrylate) (PMMA) film is stacked onto the hydrogen silsesquioxane (HSQ) resist using a dry peel and release technique, effectively circumventing the issue of HSQ solubilization by PMMA solvents typically encountered during conventional spin-coating procedures. Simultaneously, a dry lift-off technique can be implemented by eschewing the use of organic solvents during the wet process. This pioneering method enables the fabrication of high-resolution 3D free-standing plasmonic nanostructures and intricate 3D free-standing nanostructures. Finally, this study presents a compelling proof of concept, showcasing the integration of 3D free-standing nanostructures, fabricated via the described technique, into the realm of Fabry-Perot cavity resonators, thereby highlighting their potential for practical applications. This approach is a promising candidate for arbitrary 3D free-standing nanostructure fabrication, which has potential applications in nanoplasmonics, nanoelectronics, and nanophotonics.

Photodegradation of Polyethersulfone (PES), Polyvinylidene Fluoride (PVDF) and Polymethyl Methacrylate (PMMA) Microplastics via a Metal Organic Framework Namely ZIF-8/ZnO/C

The aim of this study was to photodegrade the Polyethersulfone (PES), Polyvinylidene fluoride (PVDF) and Polymethyl methacrylate (PMMA) microplastics using Zeolitic imidazolate framework-8/Zinc oxide/Carbon (ZIF-8/ZnO/C) nanocomposite generated under laboratory conditions. The produced nanocomposite was analysed using X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), X-Ray Photo Spectroscopy (XPS), Scanning Electron Microscope (SEM), Diffuse reflectance UV-vis spectra (DRS) and Electron Spin Resonance (ESR) analyses. The maximum PES, PVDF and PPMA photodegradation yields were 99%, 98%, and 96%, respectively, at 1 mg/l ZIF-8/ZnO/C nanocomposites (NCs) concentration, 1000 mg/l microplastics concentration, at pH = 10.0, at a temperature and photodegradation time of 40°C and 20 min, under oxic conditions at a sunlight intensity of 80 W/m&lt;sup&gt;2&lt;/sup&gt; and a photon yield of 16. The XRD analysis showed the generation of ZIF-8/ZnO/C, while the FTIR analysis indicated the ZnO, C, and ZIF-8.

Influence of nanohydroxyapatite mouthwash on the growth of Candida albicans biofilm on milled denture surfaces: An in vitro study.

There is a need for effective solutions for the persistent prevalence of denture stomatitis (DS) in denture-wearing populations. This study assessed the impact of nanohydroxyapatite (nanoHAP) nanoparticles on Candida albicans biofilm formation on milled polymethylmethacrylate (PMMA) denture bases. Acquired salivary pellicle was formed on disks milled from a prepolymerized PMMA puck. The disks were assigned to two groups, A (n=18) and B (n=18), and each group was further subdivided into three subgroups (6/subgroup), each treated with either Polident solution (antibacterial denture cleanser), nanoHAP mouthwash, or distilled water. Disks in group A subgroups were soaked in their respective treatment solutions for 8h, followed by biofilm formation on thedisk for 24h. Disks in group B subgroups had C. albicans biofilm formed on them for 24h, followed by soaking in their respective treatment solutions for 8h. Biofilm thickness, biomass, and live/dead cell ratio were determined using aconfocal laser scanning microscope. Biofilm morphology was examined with ascanning electron microscope (SEM). Data were analyzed by ANOVA and Tukey-Kramer multiple comparisons (α=0.05). In group A, nanoHAP mouthwash displayed significant anti-adhesive properties. In group B, biofilm biomass and thickness significantly decreased (p<0.05), with the nanoHAP showing the most substantial reduction in existing biofilm compared to other solutions, but it did not significantly affect cell viability. This study demonstrated the efficacy of nanoHAP mouthwash in inhibiting C. albicans biofilm formation when used as a storage medium for acrylic dentures. It suggests its potential clinical application for preventing denture stomatitis in patients.

The effect of attachment systems and denture cleaning methods on microbial biomass and composition in implant-supported overdentures: an experimental study

ObjectiveThis research endeavors to scrutinize the influence of attachment systems and denture cleaning methodologies on microbial biomass and composition within the realm of implant-supported overdentures, a crucial consideration for patients with dentition defects necessitating such prosthetic solutions.Subjects and methodsEmploying five polymethyl methacrylate specimens designed to emulate the fitting surfaces of traditional dentures and implant-supported overdentures. Following the polishing of each specimen and the quantification of its roughness, co-cultivation with three distinct microbial strains ensued, culminating in ultrasonic cleaning in water. The bar-clip group, differentiated by the depth of attachment, underwent cleaning employing four diverse methods. Biomass quantities were meticulously recorded both pre and post cleaning interventions, with subsequent data analysis via t-testing and one-way ANOVA, maintaining a significance level of α = 0.05.ResultsThe bar-clip groups demonstrated an elevated degree of microbial adhesion, with the deeper locator group exhibiting heightened biomass residue post-cleaning, indicative of increased cleaning complexity. Ultrasonic cleaning predominantly targeted biofilm and deceased bacteria, whereas chemical cleaners primarily reduced the quantity of viable bacteria. The synergistic application of ultrasonics and chemical cleaning treatments yielded the minimal biomass residue.ConclusionIn contemplating the utilization of dentures milled by dental computer-aided design/manufacturing systems, meticulous pre-use surface polishing is imperative. The extent of biofilm adhesion correlates with the chosen attachment system. This study advocates for the incorporation of ultrasonic cleaning in conjunction with chemical cleaning solutions to optimize the removal of biofilm and live cellular entities in the context of implant-supported overdentures.

Thermal cross section of poly(2-hydroxyethyl methacrylate) hydrogels for neutron dose calculation

Phantom materials are used to design radiation safety and protection strategies by means of numerical dose calculation. In the case of thermal neutrons, the radiation transport in the phantom relies on mass attenuation coefficients and total cross sections which are dependent on the physical and chemical properties of the material. Specifically for medical applications, such as neutron capture therapy, the neutron-induced dose is mainly related to the neutron absorption by hydrogen and nitrogen in the human tissue and body. Here, we investigate the use of poly(2-hydroxyethyl methacrylate) as a phantom material by experimental measurement and modeling of its total neutron scattering cross section and mass attenuation coefficient. We show that by varying the hydration level from 10 to 40 w%, one can obtain a neutron attenuation coefficient similar to polymethyl methacrylate or more representative of the human body, respectively. By benchmarking our phenomenological model on the experimental data, we provide a new example of how to use the average functional group approximation to accurately model total neutron cross sections in the framework of personalized medicine approaches.

The selective occurrence of ripening effect makes the cotransport of various sized nanoplastics in seawater-saturated and freshwater-saturated porous media significantly different

We explored the coadsorption and cotransport (single, binary, and ternary systems) of varying sized (50, 200, and 500 nm) Polymethylmethacrylate (PMMA) nanoplastics (NPs) with different concentration ratios in freshwater-saturated and seawater-saturated porous media. It was found that ripening effect occurred selectively, with ripening more likely to occur in seawater relative to freshwater, resulting in significantly different cotransport and coadsorption of varying sized NPs in freshwater-saturated and seawater-saturated porous media. In freshwater, there was no obvious ripening effect happening. In both binary and ternary systems, as the concentration of coexisting PMMA NPs increased, the adsorption and retention of coexisting other sized PMMA NPs were inhibited due to competition for adsorption sites. In seawater, coexisting varying sized NPs promoted adsorption and retention of each other in saturated porous media due to increased roughness and ripening effect. The NP aggregate size and the increase in surface roughness of media grains brought about by the increase in size variety of NPs dominated the cotransport of varying sized NPs in seawater-saturated porous media. The findings of this study provide help for clarifying the fate of NPs presented in real environments in porous media of freshwater and seawater systems.

Hyperbranched Organosilicon Surfactants as Emulsifiers for the Emulsion Polymerization of Methyl Methacrylate

This report is devoted to the investigation of the emulsion polymerization of methyl methacrylate in the presence of PEGylated hyperbranched polymethylethoxysiloxane as an emulsifier. It is shown that its use in the amount of 1–5 wt % affords stable 25–50% poly(methyl methacrylate) dispersions with the controlled particle sizes from 300 to 800 nm and a narrow particle size distribution.

Digital workflow in oral splint manufacturing.

The objective of the present article is to demonstrate the digital workflow used to manufacture an adjusted oral splint in a patient case. A 25-year-old female patient presented for management of her bruxism. Therefore, an adjusted oral splint was manufactured. A computer-aided motion analysis of the patient was conducted (JMA Optic). Full-arch scans of the maxilla and mandible, a biocopy of the maxilla with a bite fork, and buccal scans of the centric jaw relation (Primescan) were performed. The jaw relation was determined beforehand by ballistic closing on a chairside-fabricated anterior jig. The digital construction of a Michigan splint took place in the dental laboratory. The design was nested and milled from a polymethyl methacrylate (PMMA)-containing blank (CLEARsplint Disc). The oral splint was inserted into the patient's mouth and checked to ensure a tension-free fit. The static and dynamic contact relationship was checked. During the follow-up visit, the patient reported an improvement in tension in the masticatory muscles. The described procedure allows for the manufacture of an adjusted oral splint through a purely digital workflow.

Effect of different sintering procedures on marginal and internal fit, color, and fracture load of monolithic zirconia fixed partial prostheses.

The aim of the present in vitro study was to investigate the effects of different sintering procedures on the fit, color parameters, and fracture load of monolithic fixed partial prostheses (FPPs). A metal master model was scanned and FPPs were designed. Groups were created by fabricating FPPs using four different sintering procedures (n &#61; 10): Prettau-Standard (PST); Prettau-Slow (PSL); Ice-Speed (ISP); Ice-Standard (IST). PST-PSL (Group P; N &#61; 20) and ISP-IST (Group I; N &#61; 20) were colored with different coloring liquids. The marginal and internal fit were measured using the silicone replica method. CIELAB values of the samples were measured using a spectrophotometer. Then, for each sample, the die was obtained from polymethyl methacrylate. The specimens were cemented into dies and tested in a universal testing machine for fracture load. One-way ANOVA was performed to assess the effect of the sintering procedure on the marginal and internal fit; fracture load; and ∆E00, ∆L', ∆C', and ∆H' values of the FPPs. The PSL and PST groups showed significantly smaller internal and marginal fit values compared with the ISP group. Additionally, the internal fit values of the IST group were significantly higher than those of Group P. Sintering time reduction led to a decrease in ∆E00 values. Fracture load values were not statistically significantly affected by the different sintering procedures for both brands. Different sintering procedures did not have a clinically significant effect on fit and fracture load. Different sintering procedures were found to have an impact on the color change of monolithic zirconia restorations.

Clinico-Radiological Outcome of Percutaneous Vertebroplasty in Dorso-Lumbar Osteoporotic Vertebral Compression Fractures (OVCFs)

Introduction: Vertebral compression fractures (VCFs) are the most common complication of osteoporosis where Percutaneous vertebroplasty is thought to immediately improve the pain and disability status via stabilization and reinforcement of the fractured body with polymethylmethacrylate (PMMA) injection. Purpose: To evaluate the clinical and radiological outcome of Percutaneous vertebroplasty in osteoporotic VCFs in Dorso-Lumbar (DL) Spine. Materials and methods: It is a prospective study carried out in Bangabandhu Sheikh Mujib Medical University (BSMMU) and different private hospitals in Dhaka, from January 2010 to March 2023. Total number of patients was 121 i.e., 92 female 29 male patients (167 treated vertebrae), age ranged from 65-85 years with mean age 73.40 years. 10 cases at D10 and D11 each, 26 cases at D12, 21 cases at L1, 15 cases at L2, 16 cases at D12-L1, 03 case at D9,12, 05 cases at D10,11, 07 cases at L1,2 and 03 case at D9,12L1 and 05 cases at D12,L1,2. Follow up ranged from 24 to 36 months and outcome assessed regarding neurological status (Radiculopathy and Myelopathy), pain [Visual Analogue Score (VAS)] and disability [Oswestry Disability Index (ODI) questionnaire]. Radiological assessment of the treated spine was done to identify any vertebral height gain (McKiernan method), kyphosis correction (Cobb`s method). Results: The mean age was 73.40 ± 03.75 years. 74(60.97%) patients were in 65-74 years age group. 105(63.41%) cases had single vertebral level, 49(29.26%) with 02 levels and 12(07.32%) with 03 levels involvement. D12 (n=53, 31.17%) and L1 (n=52, 31.13%) were most frequent. The age, sex, occupation, and the level of involvement had no significant difference (p&gt;0.05, chi-squared test). VAS for pain had significantly improvement (p&lt;0.05, paired t test) from preoperative 08.50±0.50 to 03.50±0.30 postoperatively and 02.80± 0.50 at 1 year. The preoperative ODI 71.11±09.69 improved significantly (p&lt;0.05, paired t test) to 17.34±04.11 postoperatively and 09.76± 04.83% at 1 year. The kyphotic angle was corrected to 05°±02.50° at the 12 months follow up radiograph. One level (02.30%) had cement leakage which was evident on postoperative X-ray but was asymptomatic even on the last follow up. Conclusion: Percutaneous Vertebroplasty is a significantly effective technique for immediate and short-term pain relief, disability status improvement in Vertebral Compression Fractures (VCFs) with satisfactory radiological outcome in DL spine.

Photonic neuromorphic accelerators for event-based imaging flow cytometry

In this work, we present experimental results of a high-speed label-free imaging cytometry system that seamlessly merges the high-capturing rate and data sparsity of an event-based CMOS camera with lightweight photonic neuromorphic processing. This combination offers high classification accuracy and a massive reduction in the number of trainable parameters of the digital machine-learning back-end. The event-based camera is capable of capturing 1 Gevents/sec, where events correspond to pixel contrast changes, similar to the retina’s ganglion cell function. The photonic neuromorphic accelerator is based on a hardware-friendly passive optical spectrum slicing technique that is able to extract meaningful features from the generated spike-trains using a purely analogue version of the convolutional operation. The experimental scenario comprises the discrimination of artificial polymethyl methacrylate calibrated beads, having different diameters, flowing at a mean speed of 0.1 m/sec. Classification accuracy, using only lightweight digital machine-learning schemes has topped at 98.2%. On the other hand, by experimentally pre-processing the raw spike data through the proposed photonic neuromorphic spectrum slicer at a rate of 3 × 106 images per second, we achieved an accuracy of 98.6%. This performance was accompanied by a reduction in the number of trainable parameters at the classification back-end by a factor ranging from 8 to 22, depending on the configuration of the digital neural network. These results confirm that neuromorphic sensing and neuromorphic computing can be efficiently merged to a unified bio-inspired system, offering a holistic enhancement in emerging bio-imaging applications.

Experimental study on the causes of spontaneous osteogenesis of Masquelet technique induced membrane

To investigate the causes of spontaneous osteogenesis of Masquelet technique induced membrane. Forty-two male Sprague-Dawley rats aged 7-9 weeks were selected to establish a critical-sized bone defect of the right middle femur model. Then the rats were randomly divided into 4 groups, with 12 rats in groups A-C and 6 rats in group D. The bone defects in groups A-C were filled with vancomycin-loaded polymethyl methacrylate bone cement spacers. Then the Kirschner wires were used for intramedullary fixation in groups A and B, and the bone cement was used to connect the bone cement spacers and the bone ends in group B. The steel plate was used to fixation in group C. The bone defect in group D was only fixed with steel plate as a blank control group. The general condition was observed after operation. At 5 weeks after operation, 6 rats in groups A-C were selected for STRO-1 immunohistochemical staining to observe the content of mesenchyme stem cells (MSCs) in the induced membrane (STRO-1 + cells). At 12 weeks after operation, the remaining rats in groups A-D were taken for X-ray observation, gross observation, and histological observation (HE, safranin O-green staining) to observe the spontaneous osteogenesis of the membrane. All rats in the 4 groups survived until the completion of the experiment. At 5 weeks after operation, the immunohistochemical staining showed that group B was negative, while the contents of MSCs in the induced membrane in groups A and C were 14.20%±1.92% and 5.00%±0.71%, respectively, with a significant difference ( P<0.05). At 12 weeks after operation, group A showed that the new bone formed at the osteotomy site and growth towards the center of the bone defect, with an average length of 3.1 mm on one side; and the presence of bone, cartilage lesions, fibers, and a small amount of neovascularization were observed in the induced membrane. Group C only had a small amount of new bone at the osteotomy site, and a small amount of neovascularization in the induced membrane. Groups B and D did not have any new bone, but bone resorption or atrophy at the osteotomy site. Although the Masquelet technique induced membrane has osteogenesis, the key factor for the spontaneous osteogenesis is the bone marrow overflow from the bone marrow cavity providing MSCs. The spontaneous osteogenesis of the induced membrane belongs to endochondral ossification.

Effect of graphene on the key electrical, optical, and magnetic properties of polymethylmethacrylate: a study based on molecular modeling.

In this work, a new polymeric structure was designed consisting of a nanometric sheet of graphene (G) and a polymethylmethacrylate (PMMA) repeat unit, which was designated as PMMA-G. Three degrees of polymerization of PMMA-G were considered: monomer (PMMA-G1), dimer (PMMA-G2), and trimer (PMMA-G3). The effect of incorporating a nanometric sheet of graphene into the molecular structure of PMMA on the modification of some of its main optical, magnetic, and electrical properties was investigated. Currently, the study presented here is of great relevance since various areas of technology require new materials with specific properties for the development of new devices. The results of our study reveal that the dielectric constant of PMMA is reduced when graphene is incorporated. However, a percentage increase of 14.48% in the refractive index of PMMA when graphene is inserted to form the nanocomposite is observed. It is found that the absolute value of molar magnetic susceptibility of PMMA increases considerably when reinforced with graphene. Finally, when reinforcing PMMA with graphene to obtain the PMMA-G nanocomposite, the electrical resistivity increases by almost an order of magnitude. We used computational tools under Materials Studio (MS) software. We built a PMMA molecule with three degrees of polymerization, graphene sheet, and polymethylmethacrylate-graphene composite (PMMA-G) was built also with three degrees of polymerization using a concentration of 50% graphene over the PMMA polymer. For each structure, we used computational code DMol3 of MS, which is based on the Density Functional Theory, and the geometry optimization process was carried out to obtain the most stable structures. Finally, using the connectivity indices method together with topological properties of the molecular structures, implemented in Synthia computational code of MS software, we calculated the dielectric constant, magnetic susceptibility, refractive index, and electrical resistivity, for pure PMMA and PMMA-G structures for their three degrees of polymerization. The results were analyzed, and the changes in these properties were discussed in terms of the effect of an electric and magnetic field on the molecular structures of PMMA-G with respect to PMMA.

Effects of multiple reflected P waves on crack-tip stress and crack propagation in directional fracturing blasting

Directional fracturing blasting is effective for rock engineering, but it is inevitably disturbed by multiple reflected waves from different directions in natural rock mass due to discontinuous boundaries. Reflected waves affect both crack-tip stress and crack propagation, hence affect the results of directional fracturing blasting. In this paper, with the aid of high-speed photography, an optical caustics method is used to study effects of multiple reflected P waves on a directional blast-induced crack in a polymethyl methacrylate (PMMA) plate, specifically on crack path, crack fracturing mode, crack-tip stress and crack velocity. Crack-tip stress field is indicated by the shape of caustics pattern. Before the loading of reflected P waves, the mode I directional crack driven by blast-induced gases propagates in a straight path; crack-tip stress field is K-dominated, and crack-tip caustics pattern is consistent with classical caustics theory. On the contrary, under the loading of reflected P waves, the directional crack changes to be mixed-mode I + II and propagates in a curved path; Crack-tip stress field is non-K-dominated due to transient stress superposition of reflected P waves, and crack-tip caustics pattern is consistent with modified caustics theory. Transient stress superposition is not obvious for reflected P waves with a longer reflection distance. The tension loading of reflected P waves plays a more important role than the compression loading, which increases crack-tip stress intensity factors and crack velocity. This study provides a comprehensive understanding of effects of multiple reflected P waves from different directions on directional fracturing blasting.

Interaction of Polymethyl Methacrylate with Boehmite-Filmed Aluminum Cladding Under Gamma Irradiation

This paper presents an overview of ongoing work to qualify the Advanced Test Reactor (ATR) driver fuel elements that have been affected by irradiation-degraded polymethyl methacrylate (PMMA) flux wands. Irradiation testing was performed on PMMA material in contact with aluminum clad material. The cladding was prefilmed with a boehmite oxide layer, an important feature of the ATR driver fuel. The effects on the boehmite layer due to gamma irradiation of the PMMA-aluminum clad system were investigated. PMMA embrittlement, followed by softening and degradation, occurred at high radiation levels. Adhesion between the cladding and irradiated PMMA was observed. Flow testing at prototypic ATR flow rates demonstrated the effective removal of the adhered material. Measurements of the boehmite layer thickness were performed, and Raman spectroscopy was utilized to detect the presence of boehmite in the irradiated PMMA material.

Polarization‐Controlled Diffractions of Submicron Pillar Arrays of Azo Molecular Glass for Image Recording and Reconstruction

Recording and manipulating optical waves with functional structures are crucially important for many applications. Herein, the submicron pillar arrays of an azo molecular glass (IA‐Chol) are explored to show functional synergy of a recording medium and a diffractive optical element. The image recording is achieved through the pillar deformation along the electric‐field oscillation direction of incident light. When illuminated with a polarized beam, the reconstructed images appear in the first‐order diffraction spots of the pillar array with the tailored intensity distributions depending on the states of polarization of the recording beam and the image reconstruction beam. This approach enables several images to be recorded in the adjacent zones of the same pillar array using lights with different polarization directions, and then the images are reconstructed separately or simultaneously upon the polarization directions of the illumination light. Furthermore, the topographic features of the pillar array after the recording are replicated by replica‐molding to the surfaces of polydimethylsiloxane (PDMS) slices as negative replicas and transformed to surfaces of poly(methylmethacrylate) (PMMA) films through hot‐embossing. The PDMS and PMMA replicas are highly transparent in the visible light range and able to produce the reconstructed images with light in a wide‐wavelength extent.

Enhancing antifungal and antibacterial properties of denture resins with nystatin-coated silver nanoparticles

Long-term oral health issues caused by fungi and bacteria are a primary concern for individuals who wear dentures. Denture stomatitis, primarily caused by Candida albicans (C. albicans), is a prevalent condition among denture users. Metal nanoparticles exhibit improved antimicrobial effectiveness and fewer adverse effects. This study aimed to evaluate the antifungal and antibacterial effects of nystatin-coated silver nanoparticles (Nys-coated AgNPs) embedded in acrylic resin as a more biocompatible material for denture resins. AgNPs and Nys-coated AgNPs were synthesized and characterized using UV-Vis, SEM, EDX, and DLS. Specimens of polymethyl methacrylate (PMMA) with three different concentrations of Nys, AgNPs, and Nys-coated AgNPs (0.1%, 1%, 10% w/w) were prepared. The water absorption properties of the disks and drug release were investigated for 14 days and 120 h, respectively. The hydrophilic and hydrophobic properties of the samples and their contact angles were evaluated using the sessile drop technique. The antifungal and antimicrobial activity of the prepared discs was studied against C. albicans and Streptococcus mutans, respectively. Adding Nys-coated AgNPs decreased the contact angle of discs from 67° to 49°. Furthermore, the water absorption rates of the different discs were not significantly different from those of the control groups. Results showed that Nys-coated AgNPs (10% w/w) in PMMA effectively inhibited C. albicans growth better than Nys composites (10% w/w). Additionally, Nys-coated AgNPs composites, as well as AgNPs-containing composites, showed considerable antibacterial activity against S. mutans. Nys-coated AgNPs (10% w/w) had no toxic effect on NIH3T3 cells. In conclusion, Nys-coated AgNPs could be considered a good candidate for incorporation into denture resins to address chronic oral diseases.