Application of CFD modeling for indoor radon and thoron dispersion study: A review.

This paper provides an in-depth discussion of the CFD implications to the design/study of interior environments and an overview of the most widely used CFD model for indoor radon and thoron dispersion study. For the design and analysis of indoor environments, CFD is a powerful tool that enables simulation and measurement-based validation. Simulating an indoor environment involves deliberate thought and skilful management of complicated boundary conditions. User and CFD programs can develop results through gradual effort that can be relied upon and applied to the design and study of indoor environments. Radon and thoron are natural radioactive gases and play a crucial role in accurately assessing the radioactive hazard within an indoor environment. This review comprise the work related to measurement and CFD modeling on these radioactive pollutant for indoors.Highlighting the current state of environmental radioactive pollutants and potentially identified areas that require further attention or research regarding investigating factors affecting indoor radioactive pollutants.

A study on fractional HBV model through singular and non-singular derivatives.

The current study's aim is to evaluate the dynamics of a Hepatitis B virus (HBV) model with the class of asymptomatic carriers using two different numerical algorithms and various values of the fractional-order parameter. We considered the model with two different fractional-order derivatives, namely the Caputo derivative and Atangana-Baleanu derivative in the Caputo sense (ABC). The considered derivatives are the most widely used fractional operators in modeling. We present some mathematical analysis of the fractional ABC model. The fixed-point theory is used to determine the existence and uniqueness of the solutions to the considered fractional model. For numerical results, we show a generalized Adams-Bashforth-Moulton (ABM) method for Caputo derivative and an Adams type predictor-corrector (PC) algorithm for Atangana-Baleanu derivatives. Finally, the models are numerically solved using computational techniques and obtained results graphically illustrated with a wide range of fractional-order values. We compare the numerical results for Caputo and ABC derivatives graphically. In addition, a new variable-order fractional network of the HBV model is proposed. Considering the fact that most communities interact with each other, and the rate of disease spread is affected by this factor, the proposed network can provide more accurate insight for the modeling of the disease.

A technique to increase the treatment plan indices in GammaKnife: A retrospective study.

The study was to find the optimal values of priority in the inverse planning module of Leksell GammaPlan which would give better treatment plan indices in GammaKnife SRS. The study showed that the best optimised setting of the weighting or priority in the inverse planning module of Leksell GammaPlan were 0.6 for coverage, 0.3 for gradient index and 0.5 for beam on time. Inverse plans (Hybrid Inverse Plan, HIP) which were made using this optimal priority setting were compared with forward plans (FP) with all 95% coverage. The results showed that the average selectivity index (SI) was 83.05±9.68 for FP and 85.35±8.03 for HIP. So, SI improved in the HIP technique by about 2.3% compare to FP. Similarly, average gradient index (GI) for FP and HIP were respectively 2.82±0.23 and 2.76±0.33. And the average beam on time (BT) of FP and HIP were, respectively, 48.15±23.14 min and 48.35±18.09 min. So, all plan indices show improvement in the hybrid inverse planning technique over forward plans. Consequently, this will improve the quality of patient treatment in GammaKnife.

Implications on dose estimation and dispersion patterns of thoron in a typical indoor environment.

A model that describes the pollutant sources/sinks and inlet-outlet can help to assess the indoor exposure. Short half-life of radioactive thoron (220Rn) makes it vital and an interesting element to study its dispersion behavior. This work presents an extensive depiction of the influence of indoor environment thoron dispersion under fixed boundary conditions within the volume domain of 90 m3 using computational fluid dynamics (CFD) software. For the desirable air flow, inlet and outlet are considered in the room and the k-ɛ model is used. The thoron distribution is studied at different locations and different heights to cover the whole room. Obtained dispersion patterns vary at different locations and indicate non-uniformity of thoron level with elevated values in the room corners. Mean concentration was found to be 11 Bq/m3 with the exhalation rate of 0.102 Bqm-2 s-1. Some stagnant zones were found especially at the corners where the concentration is almost 5 times the average concentration. Such varying thoron level results in the overestimation and underestimation of the dose. The inhomogeneous behavior of thoron may cause variation in equilibrium factor. A simulated model is beneficial in understanding the radioactive gas behavior and has its importance in planning to find the correct dose estimation and, therefore, the best mitigation techniques.

Eco-friendly nanocellulose and its biomedical applications: current status and future prospect.

Cellulose is the earth's leading natural polymer. It is known for its properties like biocompatibility, high mechanical strength, cost-effectiveness and lightweight. Nanocellulose displays better properties as compared to the native cellulose fibre. The nanocellulose is very remunerative in the arenas of routine application especially in health care, food industry, sanitary products and many more. In the biomedical area, cellulose-based products are utilized in applications like wound healing, dental applications, drug delivery, antimicrobial material, etc. Nanocellulose biomaterials have been commercialised, representing the material of new generation. With the objective to comprehend the contribution of nanocellulose in the current status and future development in biomedical utilisations, the review is focused on cellulose, nanocellulose, types and sources of nanocellulose, its preparation, characteristics, constraints related to its composites through the analysis of certain scientific reports.

Formulation of normal tissue irradiation volumes in Co-60 and Ir-192 HDR ICBT of Ca cervix using Total Reference Air Kerma (TRAK).

AIM: The aim of this study was to formulate isodose volume relations encompassed by isodose surfaces in Co-60 and Ir-192 HDR intracavitary brachytherapy (ICBT) of cervix carcinoma using the Total Reference Air Kerma (TRAK). BACKGROUND: The TRAK and isodose volumes are radioactive source related. The formulated relations can easily estimate the irradiated isodose volume if the TRAK and dose are known. The C0-60 can also be used for brachytherapy because of its longer half life and comparable OAR doses to Ir-192. MATERIALS AND METHODS: Isodose volumes encompassed by different isodose surfaces and TRAK were obtained from 22 Ca cervix ICBT treatment plans in Co-60 and Ir-192 HDR brachytherapy with 9 Gy prescription to point A. Isodose volume relations were formulated both for Co-60 and Ir-192 brachytherapy source from the slopes and intercepts of the linear fit in the plot between isodose volumes and TRAKs. RESULTS: The TRAK value of Co-60 was higher than Ir-192 by about 7.16%. The isodose volumes at low doses for Co-60 were higher than Ir-192. But no significant differences in the dose to the bladder and rectum were observed due to these sources. For dose to 2 cm3 bladder and rectum volume, the differences were 1.07% and 0.75%, respectively. The correlation coefficient with the 2-tailed significance of correlation (p value) between TPS measured isodose volume and calculated isodose volumes using the formulated relations at different dose values were statistically significant as p < 0.05. CONCLUSION: Results show different isodose volumes for both sources but the dose to the bladder and rectum are nearly the same.

Antibacterial and antifungal activity of chitosan coated iron oxide nanoparticles.

BACKGROUND AND AIM: The emergence of resistance against antimicrobial agents has led to the development of more efficient agents and new techniques for treatment of various microbial infections. The aim of the present study is to determine the antibacterial and antifungal activity of bare and chitosan coated Fe3O4 nanoparticles (NPs) against five organisms, Escherichia coli (E. coli), Bacillus subtilis (B. subtilis), Candida albicans (C. albicans), Aspergillus niger (A. niger) and Fusarium solani (F. solani). METHODS: Fe3O4 NPs were synthesised by coprecipitation and surface coating was done by chitosan polymer to avoid agglomeration. The antimicrobial property of NPs was tested by agar well diffusion and analysed by measuring the diameter of the inhibition zone. RESULTS: Average particle size of Fe3O4 and chitosan coated Fe3O4 NPs was 10.4 ± 4.9 and 11.4 ± 5.2 nm, respectively. Mean diameter of inhibition zone of synthesised chitosan coated Fe3O4 NPs was in the range 14.5 to 18.5 mm. The effect of chitosan coated Iron oxide nanoparticles was F. solani/A. niger < C. albicans < E. coli/B. subtilis (p < 0.001). CONCLUSIONS: Chitosan coated Fe3O4 NPs are effective antimicrobial agents and so may be developed as a microbial resistant coating for biomedical devices.

Detection of Glaucoma Using Image Processing Techniques: A Critique.

OBJECTIVE: The primary objective of this article is to present a summary of different types of image processing methods employed for the detection of glaucoma, a serious eye disease. INTRODUCTION: Glaucoma affects the optic nerve in which retinal ganglion cells become dead, and this leads to loss of vision. The principal cause is the increase in intraocular pressure, which occurs in open-angle and angle-closure glaucoma, the two major types affecting the optic nerve. In the early stages of glaucoma, no perceptible symptoms appear. As the disease progresses, vision starts to become hazy, leading to blindness. Therefore, early detection of glaucoma is needed for prevention. METHODOLOGY/APPROACH: Manual analysis of ophthalmic images is fairly time-consuming and accuracy depends on the expertise of the professionals. Automatic analysis of retinal images is an important tool. Automation aids in the detection, diagnosis, and prevention of risks associated with the disease. Fundus images obtained from a fundus camera have been used for the analysis. Requisite pre-processing techniques have been applied to the image and, depending upon the technique, various classifiers have been used to detect glaucoma. CONCLUSION: The techniques mentioned in the present review have certain advantages and disadvantages. Based on this study, one can determine which technique provides an optimum result.

MEASUREMENT OF INDOOR RADON-THORON IN AIR AND EXHALATION FROM SOIL IN THE ENVIRONMENT OF WESTERN HARYANA, INDIA.

Measurement of indoor radon and thoron is important because the inhalation of radon-thoron and their daughters contributes more than 50 % of the total dose from natural sources. One of the important parameters to find out the contribution of soil and building materials towards indoor radon is radon exhalation rates, which can be used for estimation of indoor radon levels. The indoor radon and thoron levels from the air and radon exhalation rates from soil samples collected from two districts (Hisar and Fatehabad) of Western Haryana are measured using pin-hole-based radon-thoron dosimeter and LR-115 solid-state nuclear track detector by canister technique. The results show that the indoor radon and thoron levels from Hisar district varied from 11 to 112 and 11 to 80 Bq m-3, while for Fatehabad district from 5 to 24 and 59 to 105 Bq m-3, respectively, in summer season. In winter season, indoor radon and thoron levels from Hisar district varied from 15 to 43 and 32 to 102 Bq m-3, while for Fatehabad district from 18 to 31 and 11 to 80 Bq m-3, respectively. The indoor radon levels of 95 % locations lie well below the limit recommended by International Commission of Radiation Protection, 2011. The radon mass exhalation rate varied from 6 to 56 mBq kg-1 h-1 The radon mass exhalation rates from the soil samples were lower than the worldwide average, i.e. 56 mBq kg-1 h-1 There exists a poor correlation between indoor radon and exhalation rates. More investigations of measurement of radionuclide contents from rock and stone of study area can improve the understanding.

Active-passive measurements and CFD based modelling for indoor radon dispersion study.

Computational fluid dynamics (CFD) play a significant role in indoor pollutant dispersion study. Radon is an indoor pollutant which is radioactive and inert gas in nature. The concentration level and spatial distribution of radon may be affected by the dwelling's ventilation conditions. Present work focus at the study of indoor radon gas distribution via measurement and CFD modeling in naturally ventilated living room. The need of the study is the prediction of activity level and to study the effect of natural ventilation on indoor radon. Two measurement techniques (Passive measurement using pin-hole dosimeters and active measurement using continuous radon monitor (SRM)) were used for the validation purpose of CFD results. The CFD simulation results were compared with the measurement results at 15 points, 3 XY planes at different heights along with the volumetric average concentration. The simulation results found to be comparable with the measurement results. The future scope of these CFD codes is to study the effect of varying inflow rate of air on the radon concentration level and dispersion pattern.

Study of indoor radon distribution using measurements and CFD modeling.

Measurement and/or prediction of indoor radon ((222)Rn) concentration are important due to the impact of radon on indoor air quality and consequent inhalation hazard. In recent times, computational fluid dynamics (CFD) based modeling has become the cost effective replacement of experimental methods for the prediction and visualization of indoor pollutant distribution. The aim of this study is to implement CFD based modeling for studying indoor radon gas distribution. This study focuses on comparison of experimentally measured and CFD modeling predicted spatial distribution of radon concentration for a model test room. The key inputs for simulation viz. radon exhalation rate and ventilation rate were measured as a part of this study. Validation experiments were performed by measuring radon concentration at different locations of test room using active (continuous radon monitor) and passive (pin-hole dosimeters) techniques. Modeling predictions have been found to be reasonably matching with the measurement results. The validated model can be used to understand and study factors affecting indoor radon distribution for more realistic indoor environment.

Estimation of dose contribution from 226Ra, 232Th and 40K radon exhalation rates in soil samples from Shivalik foot hills in India.

The concentration of radium, thorium and potassium and radon exhalation rates in soil samples collected from Shivalik foot hills in the states of Haryana and Himachal Pradesh (India) were experimentally measured. A high-resolution gamma-ray spectroscopic system was used for the measurement of natural radioactivity ((226)Ra, (232)Th and (40)K) at Inter-University Accelerator Center, New Delhi, using a coaxial n-type high-purity germanium detector (EG&G, ORTEC, Oak Ridge, USA). The mass exhalation rates (EM) of radon in soil samples from the study area measured by 'sealed canister technique' using LR-115 type II track detectors varied from 50±1 to 143±6 mBqkg(-1) h(-1). The activity concentrations of (226)Ra, (232)Th and (40)K in various soil samples of the study area varied from 31±1.3 to 63±4.6, 53±1.8 to 78±2.6 and 472±4.8 to 630±7.0 Bq kg(-1) respectively. The results indicated some higher levels of radioactivity in Lal Dhang peak area of the hills compared with other locations under study.

Modeling of indoor radon concentration from radon exhalation rates of building materials and validation through measurements.

Building materials are the second major source of indoor radon after soil. The contribution of building materials towards indoor radon depends upon the radium content and exhalation rates and can be used as a primary index for radon levels in the dwellings. The radon flux data from the building materials was used for calculation of the indoor radon concentrations and doses by many researchers using one and two dimensional model suggested by various researchers. In addition to radium content, the radon wall flux from a surface strongly depends upon the radon diffusion length (L) and thickness of the wall (2d). In the present work the indoor radon concentrations from the measured radon exhalation rate of building materials calculated using different models available in literature and validation of models was made through measurement. The variation in the predicted radon flux from different models was compared with d/L value for wall and roofs of different dwellings. The results showed that the radon concentrations predicted by models agree with experimental value. The applicability of different model with d/L ratio was discussed. The work aims to select a more appropriate and general model among available models in literature for the prediction of indoor radon.

Environmental monitoring of radon, thoron and their progeny in some dwellings of northern Haryana (India).

The problem of randon is an important global problem of radiation hygiene concerning the world population. Radon and its progeny are the major contributors in the radiation dose received by general population of the world. Keeping this in mind, the environmental monitoring of radon, thoron and their progeny in some dwellings of northern part of Haryana state of India has been carried out. The radon thoron twin dosimeter cups were used for the study. Three pieces of LR-115 solid-state nuclear track detectors were fixed in the dosimeters and were suspended in the dwellings for three months during a season. The first detector indicated radon, thoron and progeny concentration, the second showed radon and thoron concentration, while the third detected only the radon concentration. The aim of study was to carry out possible health risk assessment in the dwellings under consideration. During summer season, the radon concentration in northern region of Haryana varied from 66-97 Bq m(-3), while the thoron concentration in the same dwellings varied from 27-65 Bq m(-3). During winter season, radon concentration in northern region of Haryana varied from 73-104 Bq m(-3) with an average of 88 + 7 Bq m(-3), while the thoron concentration in the same dwellings varied from 35-69 Bq m(-3) with an average of 55 +/- 8 Bq m(-3). The radon-thoron progeny levels and annual doses received by the inhabitants in the dwellings under study have also been calculated.

Boron based separations for in situ recovery of L-erythrulose from transketolase-catalyzed condensation.

In this article we report on the application of in situ product removal (ISPR) (the concurrent recovery of a product during the product formation process) as a means of improving the productivity of bioconversions. The Escherichia coli transketolase-catalyzed condensation of glycolaldehyde with beta-hydroxypyruvate to yield L-erythrulose (and carbon dioxide) was chosen as a model system. Those ISPR methods based on phenylboronate-diol interactions showed greatest potential for use as a selective means of removing L-erythrulose from the reaction medium. Soluble, insoluble, and immobilized boronates were investigated. Concentrations of free phenylboric acid of 100 mM and above were toxic to transketolase, thus rendering the use of these methods unsuitable for ISPR. However, one of the immobilized phenylboronate resins (Affi-Gel 601) was not toxic to the enzyme, although significant levels of nonspecific binding of both substrates were observed. When ISPR was performed on the model reaction using this resin with substrate feeding, it proceeded to completion.

Enzyme-catalysed carbon-carbon bond formation: large-scale production of Escherichia coli transketolase.

Escherichia coli strain JM107/pQR700 possesses the vector pBGS18, a high copy number plasmid carrying kanamycin resistance, into which a 4.4 kb fragment containing the transketolase gene had been cloned. The bacterium was grown at 20 and 1000 1 scale for the production of transketolase. The specific growth rate was maintained at 0.15 h-1 until the bacterial concentration reached 20 g dry wt per litre at which point the culture was harvested. The clarified cell extract obtained after disruption of the bacteria in a high-pressure homogeniser contained about 230 U ml-1 of the enzyme, which represented about 40% of the total protein released. No further purification was done at large scale as the clarified cell extract could be used satisfactorily for biotransformations.