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An evaluation of the gamma-neutron shielding capabilities of polymer nanocomposite materials based on polypropylene and iron nanoparticles is presented in this study. The chemical composition of the materials is (100-x) PP-Fex, (where x = 0.1, 0.3, 0.5, 1, 2 and 5 wt percent). For the proposed polymer samples with photon energies ranging from 30 to 2000 KeV, the mass attenuation coefficient (MAC), a crucial parameter for studying gamma-ray shielding capability, was calculated using the Geant4 Monte Carlo code. Results were compared with those predicted by EpiXS. The values of the Geant4 code and the EpiXS software were both found to be in excellent agreement. Using the mass attenuation coefficient values, we determined the linear attenuation coefficients, electron density, effective atomic number, and half value layer for all the samples. The shielding properties of the polymer samples were also evaluated by estimating both the fast neutron removal cross-section and the mean free path of the fast neutron at energies between 0.25 and 5.5 keV. The study's findings indicate a positive correlation between the Fe nanoparticle content and the gamma-ray shielding performance of PP-Fe polymer samples. Out of the several glasses that were evaluated, it was found that the PP-Fe5 polymer sample demonstrates the highest efficacy in terms of gamma-ray shielding. Moreover, the polymer sample PP-Fe5, which consists of 5 mol% of iron (Fe), exhibits the highest value of ∑R (1.10650 cm-1) and the lowest value of the mean free path for fast neutrons. This indicates that the PP-Fe5 possesses better gamma-neutron shielding efficiency.

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OBJECTIVE: The novel coronavirus (COVID-19) pandemic poses a monumental challenge to healthcare systems worldwide. Clinical features and data-driven decisions could differentiate the virus's early stages. This study aims to provide valuable diagnostic data that can help determine the severity of COVID-19 infection and allow for early detection. PATIENTS AND METHODS: A sample of 214 patients was collected to validate our approach. The data were grouped into ordinary (126 cases) or severe (88 cases) groups. The information they provided included age, gender, creatinine levels, blood pressure, glucose levels, creatine phosphokinase (CPK), alanine transaminase (ALT), cough, fever, expectoration, myalgia, headache, dyspnea, abdominal discomfort, and chest pain. Statistically, the Mann-Whitney U, T, and Chi-square tests were utilized to determine the significant differences in collected data between two groups of patients and the severity of those differences between categorical variables. RESULTS: The patients' age range was 21 to 84 years. The male gender was predominant (56%), particularly in the severe group (63.6%). The results summarized that the mortality rate for COVID-19 patients is high (4.7%). Symptomatic patients with abnormal creatinine levels, blood pressure, glucose level, CPK, ALT, cough, expectoration, dyspnea, and chest pain were significantly linked with both COVID-19 patient groups (p < 0.05). Compared to the ordinary group, patients in the severe group had abnormal creatinine levels (77.8%), high blood pressure (87.5%), diabetes mellitus (55.3%), high CPK level (85.7%), high ALT value (88.2%), cough (44.4%), expectoration (86.7%), dyspnea (81.0%), and chest pain (80.0%). CONCLUSIONS: Patients with abnormal creatinine levels, blood pressure, glucose levels, CPK, ALT, cough, dyspnea, and chest pain are at high risk for severe COVID-19 infection.

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Materials used to seal the endodontic space are subjected to enzymatic degradative activities of body fluids and bacteria. OBJECTIVES: To assess effects of simulated human salivary, blood and bacterial esterases (SHSE) on physical properties of typical restorative material and root canal sealers. METHODS: Specimens of set methacrylate-based resin composite (BisfilTM2B; RC), calcium-silicate sealer (EndoSequence®; BC) or epoxy-resin sealer (AH-Plus®; ER) were tested after up to 28Days exposure to phosphate buffered saline (PBS) or SHSE, using ANSI/ADA-57:2000 and ISO-6876:2012. RESULTS: Regardless of media, microhardness increased with time for BC remained unchanged for ER and decreased for RC (p < 0.05). SHSE moderated the increase for BC compared to PBS (28.0 ± 4.8 vs. 38.1 ± 7.9 KHN) at 7Days, and enhanced the decrease for RC at 7Days (55.6 ± 7.1 vs. 66.3 ± 6.5 KHN) and 28Days (52.3 ± 9.2 vs. 62.6 ± 8.5 KHN). Compressive strength was enhanced only for BC by either media. BC expanded with time for both incubation conditions; SHSE moderated the expansion compared to PBS at 7Days (0.026 ± 0.01% vs. 0.049 ± 0.007%). Shrinkage of ER was similar for both incubation media and was lower than that for RC (p < 0.05). Shrinkage of RC was enhanced by SHSE compared to PBS at 7Days (0.5 ± 0.07% vs. 0.38 ± 0.08%). Weight loss was lowest for ER and highest for BC (p < 0.05). It was enhanced by SHSE compared to PBS for BC at 28Days (2.40 ± 0.2 vs. 2.96 ± 0.19 W L%), and for RC at 7Days (0.54 ± 0.09 vs. 0.80 ± 0.1 W L%). SIGNIFICANCE: Simulated body fluids and bacterial esterases affected the physical properties of test materials, suggesting potential impacts on sealing ability and resistance to bacterial ingress, and tooth strength ultimately affecting their clinical performance.

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AIM: To measure collagenolytic protease activity from Enterococcus faecalis and Micrococcus luteus and their ability to degrade human dentinal collagen. METHODOLOGY: Proteases activity of E. faecalis ATCC 29212, ATCC 47077 and M. luteus towards generic and specific human matrix metalloproteinase (MMP) substrates was measured using a fluorimetric assay. The ability of the bacteria to degrade dentinal collagen was tested by quantifying the amount of hydroxyproline released into the media following incubation of the bacteria or heat-inactivated bacteria (HIN) with demineralized human dentine samples for 24 h and by scanning electron microscopy (SEM). Multifactorial anova and Tukey's post hoc test were used to analyse the data (P < 0.05). RESULTS: All strains had MMP-like activities, but with different substrate affinity; E. faecalis ATCC 29212, ATCC 47077 and M. luteus had the greatest affinity towards MMP-8 (7.75 ± 0.88 µmol L-1 /3 × 106 CFU), MMP-9 (33.86 ± 5.16 µmol L-1 /3 × 106 CFU) and generic MMP (26.08 ± 4.48 µmol L-1 /3 × 106  CFU), respectively. The amount of hydroxyproline released from demineralized dentine was similar (P > 0.05) for the three strains (range 1.8 ± 0.17 to 2.38 ± 0.39 µg 50 µL-1 ) and was significantly higher (P < 0.001) compared to their HIN counterparts (0.61 ± 0.22 µg 50 µL-1 ). SEM revealed increased collagen network degradation after incubation with bacteria versus HIN. CONCLUSIONS: Endodontic pathogens possess collagenolytic protease properties that enable them to degrade dentinal collagen, potentially compromising the restoration-tooth and sealer-tooth interfaces. These collagenolytic protease properties could facilitate the migration of pathogenic bacteria into the root canal system and explain in part their role in root canal infections.

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In regard to thermoluminescence (TL) applied to dosimetry, in recent times a number of researchers have explored the role of optical fibers for radiation detection and measurement. Many of the studies have focused on the specific dopant concentration, the type of dopant and the fiber core diameter, all key dependencies in producing significant increase in the sensitivity of such fibers. At doses of less than 1 Gy none of these investigations have addressed the relationship between dose response and TL glow peak behavior of erbium (Er)-doped silica cylindrical fibers (CF). For x-rays obtained at accelerating potentials from 70 to 130 kVp, delivering doses of between 0.1 and 0.7 Gy, present study explores the issue of dose response, special attention being paid to determination of the kinetic parameters and dosimetric peak properties of Er-doped CF. The effect of dose response on the kinetic parameters of the glow peak has been compared against other fiber types, revealing previously misunderstood connections between kinetic parameters and radiation dose. Within the investigated dose range there was an absence of supralinearity of response of the Er-doped silica CF, instead sub-linear response being observed. Detailed examination of glow peak response and kinetic parameters has thus been shown to shed new light of the rarely acknowledged issue of the limitation of TL kinetic model and sub-linear dose response of Er-doped silica CF.

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The thermoluminescence (TL) glow curves and kinetics parameters of Thulium (Tm) doped silica cylindrical fibers (CF) are presented. A linear accelerator (LINAC) was used to deliver high-energy radiation of 21MeV electrons and 10MV photons. The CFs were irradiated in the dose range of 0.2-10Gy. The experimental glow curve data was reconstructed by using WinREMS. The WinGCF software was used for the kinetic parameters evaluation. The TL sensitivity of Tm-doped silica CF is about 2 times higher as compared to pure silica CF. Tm-doped silica CF seems to be more sensitive to 21MeV electrons than to 10MV photons. Surprisingly, no supralinearity was displayed and a sub-linear response of Tm-doped silica CF was observed within the analyzed dose range for both 21MeV electrons and 10MV photons. The Tm-doped silica CF glow curve consists of 5 individual glow peaks. The Ea of peak 4 and peak 5 was highly dependent on dose when irradiated with photons. We also noticed that the electron radiation (21MeV) caused a shift of glow peak by 7-13°C to the higher temperature region compared with photons radiation (10MV). Our Tm-doped fibers seem to give high TL response after 21MeV electrons, which gives around 2 times higher peak integral as compared with 10MV photon radiation. We concluded that peak 4 is the first-order kinetic peak and can be used as the main dosimetric peak of Tm-doped silica CF.

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This study aimed to determine the prevalence of temporomandibular disorders among patients wearing dental prostheses including complete and fixed partial dentures and to evaluate the chewing ability of those patients. Questionnaire and clinical examinations were used to assess those objectives. Fifty six percent of all examined subjects exhibited at least one sign or symptom of temporomandibular disorders while 8.0% bad moderate symptoms and 10% had severe symptoms. Patients with fixed partial dentures had a significantly higher prevalence of temporomandibular disorders signs than both complete dentures and dentate. The fixed partial denture group and dentate group exhibited significantly higher chewing ability than did the complete denture group. Therefore, the type of prosthesis correlated significantly with chewing ability.

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The mass attenuation coefficients of Rhizophora spp. binderless particleboard with four different particle sizes (samples A, B, C and D) and natural raw Rhizophora spp. wood (sample E) were determined using single-beam photon transmission in the energy range between 16.59 and 25.26 keV. This was done by determining the attenuation of K(α1) X-ray fluorescent (XRF) photons from niobium, molybdenum, palladium, silver and tin targets. The results were compared with theoretical values of young-age breast (Breast 1) and water calculated using a XCOM computer program. It was found that the mass attenuation coefficient of Rhizophora spp. binderless particleboards to be close to the calculated XCOM values in water than natural Rhizophora spp. wood. Computed tomography (CT) scans were then used to determine the density profile of the samples. The CT scan results showed that the Rhizophora spp. binderless particleboard has uniform density compared to natural Rhizophora spp. wood. In general, the differences in the variability of the profile density decrease as the particle size of the pellet samples decreases.

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