A method to improve sensitivity of Ferrous ammonium sulfate - Benzoic acid - Xylenol orange (FBX) aqueous radiation dosimeter.

Ferrous ammonium sulfate - Benzoic acid - Xylenol orange (FBX) solution is known for its dosimetry properties in the dose range applicable in radiation oncology. Several attempts at improving its dose sensitivity have been reported in literature. The current work explores a novel method to improve the dose response of the system in the range 0-10 Gy with the original standard composition of the solution. Value of the sensitivity of the dosimeter was found to be 7.471/Gy with excellent linearity using the developed method. This is 115 times higher than the sensitivity obtained using the conventional methods.

Facile Synthesis, Static, and Dynamic Magnetic Characteristics of Varying Size Double-Surfactant-Coated Mesoscopic Magnetic Nanoparticles Dispersed Stable Aqueous Magnetic Fluids.

The present work reports the synthesis of a stable aqueous magnetic fluid (AMF) by dispersing double-surfactant-coated Fe3O4 magnetic nanoparticles (MNPs) in water using a facile ambient scalable wet chemical route. MNPs do not disperse well in water, resulting in low stability. This was improved by dispersing double-surfactant (oleic acid and sodium oleate)-coated MNPs in water, where cross-linking between the surfactants improves the stability of the AMFs. The stability was probed by rheological measurements and all the AMF samples showed a good long-term stability and stability against a gradient magnetic field. Further, the microwave spin resonance behavior of AMFs was studied in detail by corroborating the experimental results obtained from the ferromagnetic resonance (FMR) technique to theoretical predictions by appropriate fittings. A broad spectrum was perceived for AMFs which indicates strong ferromagnetic characteristics. The resonance field shifted to higher magnetic field values with the decrease in particle size as larger-size MNPs magnetize and demagnetize more easily since their magnetic spins can align in the field direction more definitely. The FMR spectra was fitted to obtain various spin resonance parameters. The asymmetric shapes of the FMR spectra were observed with a decrease in particle sizes, which indicates an increase in relaxation time. The relaxation time increased with a decrease in particle sizes (sample A to D) from 37.2779 ps to 42.8301 ps. Further, a detailed investigation of the structural, morphological, and dc magnetic properties of the AMF samples was performed. Room temperature dc magnetic measurements confirmed the superparamagnetic (SPM) characteristics of the AMF and the M-H plot for each sample was fitted with a Langevin function to obtain the domain magnetization, permeability, and hydrodynamic diameter of the MNPs. The saturation magnetization and coercivity of the AMF samples increased with the increase in dispersed MNPs' size of the samples. The improvement in the stability and magnetic characteristics makes AMFs suitable candidates for various biomedical applications such as drug delivery, magnetic fluid hyperthermia, and biomedicines.

Variation in Dosimeter Calibration Factor (NDW) Over a Period of 20 Years.

Long delays in renewal of calibration of secondary standards radiation dosimeters in radiation oncology centers due to the COVID19 pandemic have aroused concerns regarding accuracy in dose delivery to patients. The concerns are mainly due to the uncertainty in the absorbed dose to water calibration factor (NDW) over a period of time. In this study, the NDWfactor for two ion chambers, thimble type (Farmer) and parallel plate type (Markus), used in most of the radiotherapy centers, were retrospectively reviewed for 20 years. The calibration on all occasions except once was carried out at the Secondary Standards Dosimetry Laboratory, Bhabha Atomic Research Centre, Mumbai. The change in the NDWfactor over this period was < ±3%. We, therefore, believe that a dosimeter with no history of repairs showed reasonable stability in the NDWfactor over a long period.

Spin dynamics investigations of multifunctional ambient scalable Fe3O4 surface decorated ZnO magnetic nanocomposite using FMR.

Microwave spin resonance behavior of the Fe3O4 surface decorated ZnO nanocomposites (FZNC) has been investigated by ferromagnetic resonance (FMR). Modified hydrothermal method has been adopted to fabricate FZNC samples with Fe3O4 nanoparticles chains were used as seeds in the uniform magnetic field to decorate them on the surface of the ZnO nanoparticles in a unique configuration. Spin dynamics investigation confirms the transition of ZnO from diamagnetic to ferromagnetic as the sharp FMR spectra converts to the broad spectra with Fe3O4 nanoparticles incorporation. A single broad FMR spectra confirms that no isolated Fe3+ or Zn2+ ions exist which is also in agreement with XRD confirming suitable composite formation. Further, the increase in Fe3O4 concentration leads to decrease in g-value which is resulting from the internal field enhancement due to magnetic ordering. Also, various spin resonance parameters were calculated for the FZNC which provides a detail information about the magnetic ordering, exchange coupling and anisotropy. Elemental analysis confirms the presence of Fe and Zn simultaneously and transmission electron microscopy (TEM) image show the presence of Fe3O4 on the grain boundaries of ZnO which has been confirmed by taking high-resolution TEM and electron diffraction patterns on both sides of the interface. These unique structural configuration of the FZNC has tremendous potential in various magneto-optoelectronic, spintronics and electro-chemical applications.

Simplifying Tumor Volume Estimation from Linear Dimensions for Intra-Cranial Lesions Treated with Stereotactic Radiosurgery.

AIMS: This study aims to derive simple yet robust formula(s) for the calculation of cranial tumor volume using linear tumor dimensions in anterioposterior (AP), mediolateral (ML) and craniocaudal (CC) directions and also propose a reproducible methodology for tumor dimension measurements. MATERIALS AND METHODS: Magnetic resonance images (MRI) of 337 patients planned for Gammaknife Stereotactic Radiosurgery for different types of brain tumors were analyzed using Leksell Gamma Plan (LGP) software. Tumor volume in three dimensional was outlined and maximum tumor diameters were measured in three orthogonal directions AP, ML, and CC on the MRI. Formulas were derived to calculate tumor volume from AP, ML, and CC diameters using linear regression technique. An agreement between the calculated volume and standard volume observed from LGP software was determined using Bland Altman (B-A) plot. A comparison was made between the volume calculated using traditionally used formula of ellipsoid, standard volume obtained from LGP software and volume calculated from formulas derived in the present study. RESULTS: The tumors were divided into two categories based on their size for better volume prediction. The tumors having product of their diameters in the range 0-2.5cc were called "small tumors" and the formula proposed for their volume estimation (V = 1.513) × (AP × ML × CC) + 0.047 ) was found to predict the tumor volume with an average bias of 0.0005cc. For "large tumors," having product of diameters in the range 2.5-36cc, the proposed formula (V = 0.444 × (AP × ML × CC) + 0.339 ) predicted the tumor volume with an average bias of 0.007cc. CONCLUSIONS: The two formulas proposed in the study are more accurate as compared to the commonly used formula that considers the tumors as ellipsoids. The methodology proposed in the study for measurement of linear tumor dimensions is simple and reproducible.

Effect of Different Composite Restorations on the Cuspal Deflection of Premolars Restored with Different Insertion Techniques- An In vitro Study.

INTRODUCTION: This study was conducted to assess the effect of different composite materials on the cuspal deflection of premolars restored with bulk placement of resin composite in comparison to horizontal incremental placement and modified tangential incremental placement. AIM: The aim of this study was to evaluate the cuspal deflection caused by different composite materials when different insertion techniques were used. MATERIALS AND METHODS: Two different composite materials were used that is Tetric N Ceram (Ivoclar Vivadent marketing, India) and SonicFillTM (Kerr Sybron Dental). Forty standardized Mesio-Occluso-Distal (MOD) preparations were prepared on maxillary first premolars. Each group was divided according to composite insertion technique (n=10), as follows: Group I - bulk insertion using Tetric N Ceram, Group II - Horizontal incremental insertion technique using Tetric N Ceram, Group III- Modified tangential incremental technique using Tetric N Ceram, and Group IV- bulk insertion using SonicFillTM. Preparations were acid-etched, and bonded with adhesive resin to provide micro mechanical attachment before restoration using a uniform etching and bonding protocol in all the groups. All groups received the same total photo-polymerization time. Cuspal deflection was measured during the restorative procedure using customized digital micrometer assembly. One-way ANOVA test was applied for the analysis of significant difference between the groups, p-value less than 0.05 was considered statistically significant. RESULTS: The average cuspal deflections for the different groups were as follows: Group I 0.045±0.018, Group II 0.029±0.009, Group III 0.018±0.005 and Group IV 0.017±0.004. The intergroup comparison revealed statistically significant difference. CONCLUSION: A measurable amount of cuspal deflection was present in all the four studied groups. In general, bulkfill restoration technique with conventional composite showed significantly highest cusp deflection. There were no significant differences in cuspal deflection among sonicFillTM and modified tangential incremental insertion techniques.

Exploring the missing link - Empathy among dental students: An institutional cross-sectional survey.

BACKGROUND: Empathy plays an important role in healthy dentist and patient relationship. Hence, the aim of the study is to (a) to measure the self-reported empathy levels among dental undergraduate and postgraduate students. (b) To review the trend of changes in empathy level with experience, age, and gender among dental undergraduate and postgraduate students. MATERIALS AND METHODS: This cross-sectional, questionnaire-based study was carried out in two private dental institutions situated in Sri Ganganagar, India, with a sample size of 978. Data were obtained from the 1st to final year (BDS), interns, and postgraduate students from January to March 2015. An empathy level of students was assessed by the Jefferson Scale of Physician Empathy - Health Profession Students Version Questionnaire. An exploratory factor analysis using Kaiser's criteria was undertaken to appraise the construct validity and dimensionality. Based on the results of the factor analysis, three factors were selected; labeled as perspective taking, compassionate care, and standing in patient's shoes. RESULTS: The majority of the students was female in a equivalent  ratio of 1338:618. There were significant differences in empathy scores by gender and age (P < 0.01). The lowest and highest mean empathy scores were found in postgraduate (mean = 108.77, standard deviation [SD] =9.12) and 1st year (mean = 117.23, SD = 14.19) dental students, respectively. CONCLUSION: Dental educators should consider the likely decline in empathy among students as early as possible and adopt communication teaching strategies to promote the development of empathy and reduce the risk of further decline.