Energy X-ray Research Articles

Preparation and characterization of trivalent chromium conversion films containing Cr(NO3)3 and Co(NO3)2 on Zn-Ni electroplated films of 2024 aluminum alloy substrates

Purpose The purpose of this study is to prepare trivalent chromium conversion (TCC) film on the Zn-Ni electrodeposited film on the surface of 2024 aluminum alloy and to ensure that the TCC film has good corrosion resistance and electrical conductivity. Design/methodology/approach The morphology of the TCC film was studied by scanning electron microscopy, and the elemental composition of the TCC film was characterized by X-ray energy dispersive spectroscopy. The TCC film was tested and the roughness was analyzed by 3D morphology (white light interference). The electrochemical behavior and corrosion resistance of TCC films were studied by the Tafel polarization curve and electrochemical impedance spectroscopy, and the conductivity was tested. Findings The TCC films were uniformly black and bright in appearance and were mainly compounds of Zn, Ni and Cr with O. The electrochemical impedance of the TCC film is larger than that of the Zn-Ni film, the corrosion current (Icorr) is smaller than that of the Zn-Ni film and the corrosion potential (Ecorr) is larger than that of the Zn-Ni film, which has excellent corrosion resistance. TCCs were performed on the appropriate size of the shell sample, and the resistance of the shells was 1.5 mVDC, which meets the total resistance requirements of the test standard for composite connector accessories. Originality/value In this study, TCC film was successfully prepared on the Zn-Ni coating on the surface of 2024 aluminum alloy. The TCC film has good corrosion resistance and electrical conductivity.

Comparative impacts of myco-synthesized nanoparticles against strains of Aspergillus spp. causing biodeterioration of stored cocoa beans in Nigeria

Silver nanoparticle solutions (AgNPs) of some mushrooms: Pleurotus ostreatus, Agaricus bisporus and Agaricus campestris were prepared and characterized using Transmission Electron Microscopy (TEM), Fourier-Transform Infrared (FTIR) spectroscopy, X-Ray Diffraction (XRD) analysis and Energy Dispersive X-ray (EDX) spectroscopy. Each of the myco-sythesized AgNPs was plated against strains of Aspergillus flavus and A. ochraceous, at 5, 10 and 15% concentrations. Colour change from light yellow to orange, yellowish-brown, and reddish brown was observed after overnight incubation (at 28 °C), in the P. ostreatus, A. bisporus, and A. campestris synthesized AgNPs respectively. TEM analysis showed a spherical shape with an average size of 15.25 to 45.85 nm, 9.22 to 52.60 nm and 10.24 to 17.66 nm in P. ostreatus, A. campestris and A. bisporus AgNPs respectively. EDX spectrum showed absorption peaks of silver in the ranges of 0.8–1.4 keV, 6.2–6.6 keV, and 0.8–1.2 keV, and XRD analysis confirmed the crystalline structure of the biosynthesized AgNPs, while FTIR results revealed O–H, N–H, C=O, and C=N as the prominent functional groups. Mycelial inhibitions against A. flavus strains D28AF and D42AF ranged between 43.86–52.73% and 33.83–57.07% respectively, and were not significantly different (P ≤ 0.05) from the standard (copper sulphate). Inhibitions produced against A. ochraceous strains AOD40 and AOD45 ranged between 34.64–52.36% and 37.43–53.56% respectively and also showed similar trend in relation to the standard. This study showed that the myco-synthesized AgNPs were effective against A. flavus and A. ochraceous infecting cocoa beans at storage. They however need to be further improved for future use in the control of cocoa beans pathogens.

An Enhanced Bioactive Glass Composition with Improved Thermal Stability and Sinterability

The development of new bioactive glasses (BGs) with enhanced bioactivity and improved resistance to crystallization is crucial for overcoming the main challenges faced by commercial BGs. Most shaping processes require thermal treatments, which can induce partial crystallization, negatively impacting the biological and mechanical properties of the final product. In this study, we present a novel bioactive glass composition, S53P4_MSK, produced by a melt–quench route. This novel composition includes magnesium and strontium, known for their therapeutic effects, and potassium, recognized for improving the thermal properties of bioactive glasses. The thermal properties were investigated through differential thermal analysis, heating microscopy and sintering tests from 600 °C to 900 °C. These characterizations, combined with X-ray diffraction analysis, demonstrated the high sinterability without crystallization of S53P4_MSK, effectively mitigating related issues. The mechanical properties—elastic modulus, hardness and fracture toughness—were evaluated on the sintered sample by micro-indentation, showing high elastic modulus and hardness. The bioactivity of the novel BG was assessed following Kokubo’s protocol and confirmed by scanning electron microscopy, X-ray energy dispersive spectroscopy, and Raman spectroscopy. The novel bioactive glass composition has shown high sinterability without crystallization at 700 °C, along with good mechanical properties and bioactivity.

Impact of the fiber-optic faceplate on the imaging performance of a CMOS X-ray detector

Complementary metal-oxide-semiconductor (CMOS) active-pixel detectors are widely used in various imaging applications owing to their faster operation with lower noise and higher sensitivity than their conventional amorphous silicon-based counterparts. However, CMOS detectors are vulnerable to radiation damage owing to their crystalline structures. They also suffer from ghosting artifacts and gradual reduction of dynamic range along with their lifetime. Most CMOS detectors employ a fiber-optic faceplate (FOP) between the X-ray converter and CMOS active-pixel array to mitigate the radiation effect and increase longevity. In this study, we investigated the effect of an additional FOP layer on the imaging performance of a CMOS detector, including the modulation-transfer function (MTF), noise-power spectrum (NPS), and detective quantum efficiency (DQE). For X-ray energies ranging from 40 to 70 kV, we measured the large-area signal-transfer functions, MTFs, and NPSs and calculated the corresponding DQEs. The FOP degraded the MTF performance over the entire spatial frequency, but improved the NPS performance with increasing spatial frequency. Consequently, the FOP layer enhanced the DQE performance for the given energy ranges. The measured results are discussed in detail using a theoretical cascaded-systems model.

Image-based finite element model stiffness and vBMD by single and dual energy CT reconstruction kernel

Single-energy quantitative computed tomography (SEQCT) provides volumetric bone mineral density (vBMD) measures for bone analysis and input to image-based finite element models (FEMs). Dual-energy CT (DECT) improves vBMD by accounting for voxel-specific material variations utilizing scans at multiple x-ray energies. vBMD is also altered by reconstruction kernel that cannot be accounted for using calibration phantoms. This study compared vBMD and FEM stiffness derived from SEQCT and DECT images reconstructed with two common kernels. SEQCT and DECT images of cadaveric shoulders (n = 10) were collected using standard (STD) and boneplus (BONE) kernels. Hounsfield Units were converted to vBMD using specimen-specific calibrations. DECT STD and BONE images were generated using an established material decomposition method with 40 and 90 keV simulated monochromatic images. A proximal humerus bone section below the anatomic neck was used for vBMD analysis and FEM generation. FEMs were loaded to 1 % apparent strain for stiffness measurements.Between STD and BONE kernel images, average vBMD differed 0.9 mgK2HPO4/cc and 4.1 mg K2HPO4/cc, in SEQCT and DECT images, respectively. Significant differences occurred in DECT images (p = 0.001). BONE reconstructed images produced higher vBMD measures across both SEQCT and DECT images. The difference between STD and BONE in both SEQCT- and DECT-based FEMs persisted, with larger estimated stiffness in BONE models. For six of the models DECT-based had higher stiffness than SEQCT-based models using the same kernel, although these models differed between STD and BONE kernels. Differences in stiffness between STD and BONE derived models were similar across image types (DECT: 17.5 kN/mm; SEQCT: 19.0 kN/mm). Stiffness values were significantly different within SECT kernels and between SEQCT BONE and DECT STD models. This study shows important differences in vBMD and FEM stiffness that occur due to CT-based imaging parameters alone. These results indicate that consistent imaging parameters should be used for vBMD analysis and FEM input to avoid systematic measurement errors.

Co–Ni nanoparticle supported on heteroatom-doped carbon derived from garlic powder and eutectic solvent: Its application in Nitroarenes reduction

This paper presents the synthesis of a novel heterogeneous catalyst, PSN-C600-Co2:Ni1, designed for the hydrogenation of nitroaromatic compounds. The catalyst is a porous carbon substrate triply doped with nitrogen, sulfur, and phosphorus, incorporating bimetallic Co and Ni nanoparticles. A natural precursor, garlic biochar, and a biodegradable eutectic solvent were used in the synthesis. Various characterization techniques, including Scanning Electron Microscope (SEM), X-Ray Energy Diffraction Spectroscopy (EDX), Elemental Mapping Measurements (MAP), Thermogravimetric Analysis (TGA), X-Ray Diffraction (XRD), Infrared Spectrometer (FTIR), Transmission Electron Microscope (TEM), Raman Spectroscopy, and Nitrogen Adsorption and Desorption Pattern (N2 adsorption-desorption isotherm), were utilized to examine the features and properties of the synthesized PSN-C600-Co2:Ni1 catalyst.

Study of the High-Temperature Sintering Characteristics of Boron Oxide Composite Silicon-Based Ceramics

This paper explores the application of boron oxide (B2O3) as a sintering additive in silicon-based (SiO2) ceramics, focusing on its impact on the sintering process and resulting ceramic properties. Composite silicon-based ceramic shells with boron oxide content ranging from 0 to 4 Wt% were prepared using digital light processing (DLP) technology. This study examines the effects of boron oxide on sintering temperature, apparent porosity, shrinkage rates, and mechanical properties during high-temperature sintering. Experimental results indicate that, as boron oxide content increases, the shrinkage rate of the ceramic samples rises progressively, with shrinkage in the XY direction increasing from 4.57% to 16.40% and in the Z direction from 6.25% to 17.03%. Concurrently, the apparent porosity decreases with higher boron oxide content, ranging from a maximum of 36.17% to a minimum of 23.27%. Bulk density also improves from 1.49 g/cm3 to 1.78 g/cm3. The bending strength trend first rises and then declines, peaking at 15.39 MPa at a boron oxide content of 3 Wt%. X-ray Diffraction and Energy Dispersive Spectroscopy analyses confirm that the addition of boron oxide promotes the formation of beta-quartz and that its liquid-phase behavior at high temperatures aids in enhancing ceramic densification. This study demonstrates that an appropriate amount of boron oxide can effectively lower the sintering temperature of silicon-based ceramics while improving their mechanical properties, providing a theoretical foundation and practical basis for broader industrial applications.

Response of CaSO4:Dy Teflon embedded thermoluminescent dosimeter badge on different ISO phantoms for photons and beta sources using FLUKA and GEANT4

In this study, Monte Carlo codes FLUKA and GEANT4 were used to assess the angular variation in the response of CaSO4:Dy Teflon disc based TLD badge. These badges were positioned on various ISO phantoms to simulate the angular exposures ranging from 0° to 60° for photons within the energy range of 12.3 keV to 1.25 MeV, as well as for 90Sr/90Y and 106Rh/106Ru beta sources. Plots showing the TL response of the discs in terms of Hp(10), Hp(3), and Hp(0.07) as a function of photon energy were obtained for ISO slab, cylindrical, and pillar phantoms, respectively. Additionally, the study estimated the angular variation in the response of disc ratios (R12 and R32) with respect to both photon and beta energies. The simulation results revealed that the response of the open disc (D3) was higher for lower X-ray energies, attributed to an increase in the photoelectric effect. Conversely, the response of the disc under the metal filter (D1) was observed to increase with the angle, indicating the Compton scattering from the cassette body and phantom, especially at lower X-ray energies. Beta response of both disc D2 (under PMMA filter) and D3 found to be decreasing with the angle of incidence while R32 ratio found to be increasing with the angle of incidence for both 90Sr/90Y and 106Rh/106Ru beta sources. Notably, the simulated results demonstrated good agreement with experimental observations, reinforcing the reliability of the Monte Carlo simulations for complex interactions and responses of TLD badges under different irradiation conditions.

Development, characterization and radiation dosimetry evaluation of Bovine gelatin crosslinked with Gum Arabic Aldehyde as brain phantom gel material in radiation therapy

Brain phantom gel materials are of critical importance for accuracy of dosimetry, treatment planning and quality assurance in radiotherapy. Development of reliable and realistic phantoms enhances improved radiotherapy practices. Gel dosimeters have unique property to record radiation dose distribution in three dimensions. Polymer gels also have added advantages for brachytherapy dosimetry. Objective of the study was to develop an alternative polymeric gel material equivalent to human brain for conducting radiation dosimetry studies in radiotherapy. Hydrogel prepared from gelatin and gum arabic aldehyde was used to develop a brain phantom gel material for radiation dosimetry in radiotherapy. The results of comparative studies with G-GAAB gel strongly suggest, the gel can successfully be utilized as a brain equivalent material for radiation dosimetry in place of standard water phantom by measuring (a) CT number values (b) mass attenuation coefficient values at two X-ray energies used in radiation treatment (c) absorbed dose values at different depths for various setup conditions. The midrange CT number values inside gel material and that of human brain measured from CT images were 25.5HU and 25HU respectively with a variation of 2%. The mass attenuation coefficients for brain, water and gel material at 6MV photons were 0.0275cm2/g, 0.0280cm2/g,0.0270cm2/g and for 15MV photons, the attenuation coefficients were 0.0192cm2/g, 0.0190cm2/g and 0.0180cm2/g respectively. The percentage deviation of all measurements of absorbed dose values in gel phantom material, compared with the values of standard water phantom at various radiation dosimetry setup parameters, is less than 2%.

Utilizing High X-ray Energy Photon-In Photon-Out Spectroscopies and X-ray Scattering to Experimentally Assess the Emergence of Electronic and Atomic Structure of ZnS Nanorods.

The key to controlling the fabrication process of transition metal sulfide nanocrystals is to understand the reaction mechanism, especially the coordination of ligands and solvents during their synthesis. We utilize in situ high-energy resolution fluorescence detected X-ray absorption spectroscopy (HERFD-XAS) as well as in situ valence-to-core X-ray emission spectroscopy (vtc-XES) combined with density functional theory (DFT) calculations to identify the formation of a tetrahedral [Zn(OA)4]2+ and an octahedral [Zn(OA)6]2+ complex, and the ligand exchange to a tetrahedral [Zn(SOA)4]2+ complex (OA = oleylamine, OAS = oleylthioamide), during the synthesis of ZnS nanorods in oleylamine. We observe in situ the transition of the electronic structure of [Zn(SOA)4]2+ with a HOMO/LUMO gap of 5.0 eV toward an electronic band gap of 4.3 and 3.8 eV for 1.9 nm large ZnS wurtzite nanospheres and 2 × 7 nm sphalerite nanorods, respectively. Thus, we demonstrate how in situ multimodal X-ray spectroscopy and scattering studies can not only resolve structure, size, and shape during the growth and synthesis of NPs in organic solvents and at high temperature but also give direct information about their electronic structure, which is not readily accessible through other techniques.

Research evaluation of some properties of HDX-24 porous metal mechanical frame material

This paper introduces the results of the research on the fabrication of HDX-24 porous metal-mechanical framework material using 4,4'-Bipyridine-2,6,2',6'-tetracarboxylic acid (H4L). The properties of post-fabrication materials are studied through a number of modern research methods such as Scanning electron microscopy (FE-SEM), BET-specific surface area determination, TGA thermogravimetric analysis, X-ray diffraction spectroscopy (XRD), X-ray energy scattering spectroscopy (EDS), etc. Fourier Transform Infrared Spectroscopy (FT-IR). The results show that HDX-24 material has a specific surface area-BET of 239.06 m2/g, the adsorption capacity of the material reaches 5.2 mmol/g, the particle size reaches 75-78 mm, and the pore volume is 0.202 cm3/g.

Facile synthesis of CuCo2O4@CdS nanoheterostructure for asymmetric supercapacitor

The abundant active sites, high theoretical capacitance, and cost-effective synthesis of transition metal oxides@sulfides (TMOs@TMSs) have made them a highly desirable choice as active electrode materials for supercapacitors. This study demonstrated the successful fabrication of a CuCo2O4@CdS nanoheterostructure electrode using a simple and economical co-precipitation method The morphology, physicochemical properties, and electrochemical behavior of this electrode were subsequently studied. The synthesized CuCo2O4@CdS nanoheterostructure was characterized using Infrared Fourier-transform spectroscopy, X-ray diffraction, Raman spectroscopy, energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, High-resolution transmission electron microscopy, N2 adsorption/desorption isotherms and atomic force microscopy. The electrochemical performance was studied using cyclic voltammetry, impedance spectroscopy, and galvanostatic charge-discharge (GCD) measurements with a 6 Molar KOH aqueous electrolytic solution. Results from powder X-ray diffraction pattern and energy dispersive X-ray revealed the formation of CuCo2O4@CdS nanoheterostructure. Furthermore, SEM images showed the formation of more spherical structures in nanoheterostructure. The results of optical measurements of thin films were analyzed, which showed an increase in the energy gap (Eg) of CuCo2O4 nanoparticles when combined with cadmium sulfide (CdS). Additionally, the intensity of photoluminescence of the CuCo2O4@CdS nanoheterostructure was lower compared to the pure nanoparticles. Moreover, the newly synthesized CuCo2O4@CdS nanoheterostructure showed a specific capacitance of 257.5 F g−1 at a current density of 0.5 A g−1 via a three-electrode galvanostatic charge-discharge system, respectively. In the asymmetric device, the supercapacitor yielded an optimum energy density and power density of 19.6 Wh kg−1 and 700 W kg−1 at 1 A g−1 current density, respectively. Although the capacitance retention was maintained at nearly 85.2 % after 4000 cycles at a current density of 3 A g−1.

Reductive mechanochemical synthesis of alkali molybdenum bronze nanoparticles

The synthesis of two mixed-valent oxides of Mo using mechanochemical methods was presented. The reactions proceed via two-steps including ball milling and an annealing step. Two alkali molybdenum oxides bronzes of special interest, K0·3MoO3 and Na0.9Mo6O17 were considered. The structures and stoichiometry are supported by powder X-ray diffraction and energy dispersive X-ray spectroscopy measurements. It was found that the effects of ball milling significantly reduce the time required (from 12 or more to 4 h) to complete the reaction by creating solid solutions which dramatically lower the melting point of MoO3 from around 800 °C–400 °C. Additionally, we demonstrate the use of ball milling to synthesize nanoparticles of these bronzes with controlled size distributions, with average length down to 7.7 ± 2.5 nm; shown by pXRD and transmission electron microscopy measurements. The results demonstrate the possibilities for reducing total reaction times necessary for the formation of complex oxides by combining mechanochemical methods with additional synthetic routes. This methodology, as well as the ability to control product size, enables further investigation of size-dependent electronic phenomena in these systems.

Pulsed N2 plasma surface treatment for AlGaN/GaN HEMTs prior to PECVD SiNx passivation to reduce plasma damage

In this work, a pulse-mode N2 plasma surface treatment process was proposed as a means of reducing plasma damage and improving the GaN/GaOx ratio on the surface before SiNx deposition, which further contributes to an enhanced density of 2DEG and a reduced sheet resistance. With the pulsed N2 plasma surface treatment combined with subsequent SiNx passivation, the fabricated GaN HEMTs exhibit negligible current collapse and suppressed leakage current. The improved behavior is attributed to the fact that the pulsed N2 plasma is capable of nitriding the surface and removing carbon contaminants as identified through x-ray photoelectron spectroscopy and energy dispersive x-ray spectroscopy. Compared to the traditional continuous-wave-mode N2 plasma, the pulsed N2 plasma pre-treatment effectively prevents continuous collisions of the plasma during acceleration, thereby significantly reducing plasma damage. This work offers valuable insights for surface treatment processes in micro- and nanofabrication.

Feasibility of PET-enabled dual-energy CT imaging: First physical phantom and initial patient study results.

Dual-energy (DE) CT enables material decomposition by using two different x-ray energies and may be combined with PET for improved multimodality imaging. However, this increases radiation dose and may require a hardware upgrade due to the added second x-ray CT scan. The recently proposed PET-enabled DECT method allows dual-energy imaging using a conventional PET/CT scanner without the need to change scanner hardware or increase radiation exposure. Here we demonstrate the first-time physical phantom and patient data evaluation of this method. The PET-enabled DECT method reconstructs a gamma-ray CT (gCT) image at 511keV from the time-of-flight PET data with the maximum-likelihood attenuation and activity (MLAA) approach and then combines this image with the low-energy x-ray CT images to form a dual-energy image pair for material decomposition. To improve the image quality of gCT, a kernel MLAA method was developed using the x-ray CT as a priori information. Here we developed a general open-source implementation for gCT reconstruction and used this implementation for the first real data validation using both physical phantom study and human-subject study. Results from PET-enabled DECT were compared using x-ray DECT as the reference. Further, we applied the PET-enabled DECT method in another patient study to evaluate bone lesions. Compared to the standard MLAA, results from the kernel MLAA showed significantly improved image quality. PET-enabled DECT with the kernel MLAA was able to generate fractional images that were comparable to the x-ray DECT, with high correlation coefficients for both the phantom study and human subject study (R > 0.99). The application study also indicates that PET-enabled DECT has potential to characterize bone lesions. Results from this study have demonstrated the feasibility of this PET-enabled method for CT imaging and material decomposition. PET-enabled DECT shows promise to provide comparable results to x-ray DECT.

Influence of Ag-concentration on TiO2-supported catalysts for photocatalytic degradation of microplastics PA66 in marine

Over the past few years, microplastics pollution in marine environments has become a global concern. In this study, a series of silver-doped titanium dioxide (Ag/TiO2) photocatalysts were prepared by the photo-assisted deposition method as an alternative approach for the rapid removal of microplastics particles from aqueous media, specifically polyamide 66 (PA66), the major type of microplastics in marine. The physicochemical and optical properties of photocatalysts were analyzed by Scanning Electron Microscopy (SEM), X-ray Energy Dispersion Spectrum (EDS), X-ray Diffraction (XRD), Photoluminescence Spectroscopy (PL), and Ultraviolet-visible Diffuse Reflectance Spectroscopy (UV–vis DRS). The characterization results of the photocatalysts indicated that the appropriate loading of Ag on TiO2 significantly enhanced the optical properties of the catalysts. Specifically, 1.5 % Ag/TiO2 (AT1.5) exhibited the best light absorption performance and the lowest bandgap value, effectively suppressing the recombination of photogenerated electron-hole pairs. Furthermore, a series of photocatalytic degradation experiments confirmed that AT1.5 exhibited optimal performance in degrading PA66. Under UVA irradiation for 4 hours, the photocatalytic degradation of PA66 by AT1.5 resulted in a mass loss of 58.9 %. The degradation rate of PA66 increased with the amount of catalyst. When the mass ratio of AT1.5 to PA66 was 3:1, PA66 experienced 100 % mass loss after 4 hours of UVA exposure. Finally, through qualitative analysis, this study proposed the possible pathways and mechanisms for the photocatalytic degradation of PA66 by Ag/TiO2. Despite the challenges posed by microplastics pollution to marine ecosystems, this research provides a rapid and effective degradation method.

A cascade X-ray energy converting approach toward radio-afterglow cancer theranostics.

Leveraging X-rays to initiate prolonged luminescence (radio-afterglow) and stimulate radiodynamic 1O2 production from optical agents provides opportunities for diagnosis and therapy at tissue depths inaccessible to light. However, X-ray-responsive organic luminescent materials are rare due to their intrinsic low X-ray conversion efficiency. Here we report a cascade X-ray energy converting approach to develop organic radio-afterglow nanoprobes (RANPs) for cancer theranostics. RANPs comprise a radiowave absorber that down-converts X-ray energy to emit radioluminescence, which is transferred to a radiosensitizer to produce singlet oxygen (1O2). 1O2 then reacts with a radio-afterglow substrate to generate an active intermediate that simultaneously decomposes to emit radio-afterglow. Through finetuning such a cascade, intraparticle radioluminescence energy transfer and the 1O2 transfer process, RANPs possess tunable wavelengths and long half-lives, and generate radio-afterglow and 1O2 at tissue depths of up to 15 cm. Moreover, we developed a biomarker-activatable nanoprobe (tRANP) that produces a tumour-specific radio-afterglow signal, leading to ultrasensitive detection and the possibility of surgical removal of diminutive tumours (1 mm3) under an X-ray dosage 20 times lower than inorganic materials. The efficient radiodynamic 1O2 generation of tRANP permits complete tumour eradication at an X-ray dosage lower than clinical radiotherapy and a drug dosage one to two orders of magnitude lower than most existing inorganic agents, leading to prolonged survival rates with minimized radiation-related adverse effects. Thus, our work reveals a generic approach to address the lack of organic radiotheranostic materials and provides molecular design towards precision cancer radiotherapy.

Optimizing radiation dosimetry: Impact of PMMA layers on electronic equilibrium for the calibration of radiation protection instruments

In radiation dosimetry, achieving electronic equilibrium is vital for accurate dose measurements in radioprotection. This study investigates the effect of Poly Methyl Methacrylate (PMMA) layers, known by its chemical formula C5H8O2 and a density of 1.19 g/cm³ (PNNL, 2011), on electronic equilibrium for the calibration of radiation protection instruments, focusing on photon beams of varying energies. Using DOSIMEX 2.0 simulation software, we modeled the influence of PMMA thickness on calibration factors across different X-ray and gamma-ray beam energies. Experimental validation with Cs-137 and Co-60 sources confirmed the reliability of the simulation. Our results highlight that while PMMA layers have a minimal impact on calibration for higher-energy beams, their role becomes significant for energies below 40 keV. For X-ray beams (From 30 to 140 kV), the results show minimal calibration factor deviation (<1.6%), whereas radionuclide beams exhibit more significant variations (4.1%), necessitating customized calibration approaches. This study underscores the importance of adhering to ISO 4037-3 standards in radioprotection, particularly in low-energy scenarios, to ensure the precision of calibration procedures and optimize radiation protection practices. Furthermore, based on the results obtained, the absence of PMMA does not have a dramatic effect on the calibration of X-ray radiation instruments, whereas for gamma-ray beams, it has a significant impact.

Effect of ultraviolet treatment on soft tissue healing and bacterial attachment to titania-coated zirconia

Zirconia is the most promising implant abutment material due to its excellent aesthetic effect, good biocompatibility and corrosion resistance. To obtain ideal soft tissue sealing, the implant abutment surface should facilitate cell adhesion and inhibit bacterial colonization. In this study, pre-sintered zirconia was placed in a suspension of titania (TiO2) and zirconium oxychloride (ZrOCl2) and heated in a water bath for dense sintering. A titania coating was prepared on the zirconia surface and subjected to UV irradiation. The surface morphology, elemental composition and chemical state of each group of samples were analyzed by scanning electron microscope, x-ray energy spectrometer, x-ray photoelectron spectroscopy and x-ray diffraction. The responses of human gingival fibroblasts (HGFs) and common oral pathogensStreptococcus mutans(S. mutans) andPorphyromonas gingivalis(P. gingivalis) to modified zirconia were systematically assessed. Our findings demonstrated that the surface of titania-coated zirconia after UV irradiation produced a large number of hydroxyl groups, and its hydrophilicity was significantly improved. Meanwhile, the UV irradiation also greatly removed the hydrocarbon contaminants on the surface of the titania-coated zirconia. The UV-treated titania coating significantly promoted the proliferation, spreading, and up-regulation of adhesion-related genes and proteins of HGFs. Furthermore, the titania coating irradiated with UV could reduce the adhesion, colonization and metabolic activity ofS. mutansandP. gingivalis. Therefore, UV irradiation of titania-coated zirconia can promote the biological behavior of HGFs and exert a significant antibacterial effect, which has broad clinical application prospects for improving soft tissue integration around zirconia abutments.

Dual-doped metalloporphyrin MOFs-based nanoagent increases low-dose radiotherapy efficacy by apoptosis-ferroptosis for hepatocellular carcinoma

Radiotherapy (RT) represents a cornerstone therapeutic approach in clinical practice for locally control of hepatocellular carcinoma (HCC). However, its efficacy in treating liver cancer is significantly hampered by radiation resistance, which attributed to the insufficient reactive oxygen species (ROS) generation within the tumor microenvironment (TME). To augment RT efficacy, we have developed a novel radiosensitizer termed PTFM. The compound has the features of meso-tetra (4-carboxyphenyl) porphine (TCPP) porphyrin metal–organic frameworks (MOF, PCN-224(Fe)) co-doped with high-atomic element Ta. Under X-ray excitation, the porous PTFM acts as a proficient radio-sensitization, absorbs X-ray energy to promote hydroxyl radicals generation for RT, thereby disrupting the redox balance and intensifying the cytotoxic effect on tumor cells. The incorporation of Fe3+ into the macrocycle of TCPP within the MOFs shell, facilitates the reactions with GSH and H2O2 in the TME, leads to ROS production that promotes ferroptosis and apoptosis, while also releases O2 to alleviate tumor hypoxia. Furthermore, PTFM with thermo-metal serves as a dual-mode MR/CT imaging contrast agent, enabling precise RT monitoring and imaging guidance. In conclusion, the radiosensitizer we developed integrates dual-mode imaging capabilities and enhances RT sensitization for HCC through ROS-induced cell apoptosis and ferroptosis, thereby ameliorating tumor hypoxia.