Analysis of the CSF model for simulated loss of coolant accident conditions

An experimental facility called Containment Studies Facility (CSF) has been constructed at the Bhabha Atomic Research Centre (BARC) for the purpose of research and development in the area of nuclear reactor containment thermal hydraulics. The facility consists of reinforced concrete containment structural model (CM) and a Primary Heat Transport Model (PHTM) vessel. The containment model of CSF is divided into high enthalpy V1 volume (dry well) and low enthalpy V2 volume (wet well). The PHTM and associated pump and piping system is designed for simulating the Loss of Coolant Accident (LOCA) conditions within the containment model. Experiments were carried out in CSF for 30 bar and 50 bar blowdown conditions. Pressure, temperature and other transient parameters were recorded. The experimental results were compared with outputs of modeling carried out using RELAP code and in-house containment thermal hydraulic code CONTRAN.

Multiple receptor tyrosine kinases converge on microRNA-134 to control KRAS, STAT5B, and glioblastoma

Receptor tyrosine kinases (RTKs) are co-deregulated in a majority of glioblastoma (GBM), the most common and most deadly brain tumor. We show that the RTKs MET, EGFR, and PDGFR regulate microRNA-134 (miR-134) in GBM. We find that miR-134 is downregulated in human tumors and cancer stem cells and that its expression inversely correlates with the activation of MET, EGFR, and PDGFR. We demonstrate that miR-134 inhibits cancer cell and stem-cell proliferation, survival, and xenograft growth, as well as cancer stem-cell self-renewal and stemness. We identify KRAS and STAT5B as targets of miR-134, and establish molecular and functional links between RTKs, miR-134, KRAS/STAT5B and malignancy in vitro and in vivo. We show that miR-134 induction is required for the anti-tumor effects of RTK inhibitors. We also uncover the molecular pathways through which RTKs regulate miR-134 expression and demonstrate the involvement of MAPK signaling and the KLF4 transcription factor. We therefore identify miR-134 as a novel RTK-regulated tumor-suppressive hub that mediates RTK and RTK-inhibitor effects on GBM malignancy by controlling KRAS and STAT5B.

Fetal hemoglobin and alpha thalassemia modulate the phenotypic expression of HbSD-Punjab

INTRODUCTION

HbSD-Punjab (HbSD) is a less common form of sickle cell disease (SCD) and discrimination between HbSD and HbSS is not possible on alkaline electrophoresis because the two variants overlap in the compound heterozygous state. There are only a few publications consisting mostly of case reports. Thus, the phenotypic expression of HbSD and its modifiers has not been studied.

METHODS

We studied the phenotypic expression of 42 cases of HbSD (the largest number of subjects ever included in this kind of study) and compared them with 84 HbSS cases matched for age, sex, and caste. Further, we evaluated the influence of HbF concentration and alpha thalassemia on the phenotypic expressions of HbSD, namely the frequency of VOC and degree of hemolysis.

RESULTS

The frequencies of VOC were similar in both the groups. The markers of hemolysis such as total bilirubin, unconjugated bilirubin, and LDH were higher where as HbF concentration was significantly low in HbSD. There was a negative correlation between HbF concentration and risk of VOC in the HbSD. The total hemoglobin level and hematocrit were significantly high, and the MCV and MCH were significantly low in HbSD with alpha thalassemia. Alpha thalassemia had no influence on the frequency of VOC and severity of hemolysis in HbSD.

CONCLUSION

HbF reduced the frequency of VOC but had no influence on the hemolytic markers in HbSD. HbSD with alpha thalassemia was associated with hypohromic and microcytic features of red blood cells.

Unilateral Hypoplastic Kidney in a Case of Holt-Oram Syndrome

Holt-Oram syndrome (HOS) is characterised by skeletal abnormalities of the upper limb & congenital cardiac defects. Here we report a case of one day old male baby with skeletal abnormalities of forearms and hands, atrial septal defect of ostium secundum type and unilateral hypoplastic kidney. Till date, other associated anomalies like extra-hepatic portal hypertension, renal artery malformations etc have been reported with Holt-Oram syndrome, but it is the first case to be reported in association with hypoplastic kidney. DOI: http://dx.doi.org/10.3126/jnps.v33i1.7127 J Nepal Paediatr Soc. 2013;33(1):77-79

Blood biomarkers in metal scrap workers accidentally exposed to ionizing radiation

The detrimental effect of nuclear accidents due to localized or whole body radiation exposure results in severe cellular damage. The current study was carried out to evaluate radiation-mediated variability in blood components of metal scrap workers exposed accidently to cobalt-60 source. Blood samples collected initially from five hospitalized patients, coded P1–P5, were processed for total leukocyte counts (TLC), platelet (PLT) counts, haemoglobin, estimation of DNA double strand breaks by measuring phosphorylated form of H2AX (γ-H2AX) and chromosomal aberrations (dicentrics). Blood cells count (TLC), in all the patients except P2, was found decreased. Dicentrics increased in all the five patients. γ-H2AX was found significantly elevated in patients P2 and P4. After 3 days, 21 subjects working in close vicinity of accident site were evaluated for the above-mentioned markers to confirm their possibility of radiation exposure; however, all the parameters in these subjects were found within normal limits. Blood from patients P1–P5 was collected again after 11 days. Studies revealed exorbitant increase in γ-H2AX in lymphocytes and monocytes of patients P1, P4 and P5. TLC and PLT count in these patients had fallen further. Dicentrics declined with time in all the five patients. Based on the studied blood biomarkers, we conclude that the five subjects showed signs of radiation exposure. Measurement on radiation dose could not be performed in the current study; however, the generated data particularly on dicentrics provide ample evidence of radiation exposure.

Preliminary evaluation of effect of Engineered Safety Features on source term for AHWR containment

The proposed Advanced Heavy Water Reactor (AHWR) employs double containment envelope along with many Engineered Safety Features (ESFs) to mitigate the consequences of Loss-of-Coolant Accidents (LOCA) with safety system failure, during which high enthalpy steam and radioactive fission products will be discharged into the containment. In such conditions, the pressurized containment will be the source of activity release to the environment by way of leakage. It is required to study the effect of ESFs on the source term from the AHWR containment. An analysis was performed to evaluate the release rate from the AHWR containment during a postulated accident with the in-house containment code CONTRAN and the aerosol behavior code NAUA5-M in a coupled way. Modules for simulating the engineered safety features were incorporated in the CONTRAN code and the aerosol transport behaviour was evaluated using NAUA5-M separately. The AHWR containment is divided into three nodal volumes interconnected by junctions. The blow down mass, energy discharge data and activity released into the containment from the reactor core, for a postulated LOCA case of 200% RIH break with failure of shutdown systems (1 & 2), are inputs to the CONTRAN code. Thermodynamic parameters like containment gas temperature, partial pressure of steam, air in the subdivided volumes along with the flow rates through junctions obtained from CONTRAN were supplied to NAUA5-M. An analysis was carried out for a number of cases, postulated based on availability/unavailability of ESFs. Pressure, temperature and activity concentration transients were evaluated, for 72 h, in the subdivided volumes along with the activity released out of the containment through leakages and stack discharges for all the cases. This paper highlights the importance of operation of ESF in reducing the activity release to the environment.

Simulation model of a nuclear power plant turbine

A computer code “TURDYN” has been developed for prediction of high pressure and low pressure turbine torque under thermodynamic transient conditions. The model is based on the conservation laws of mass and energy. All the important components of turbine systems, e. g. high pressure turbine, low pressure turbine, feed heaters, reheater, moisture separator have been considered. The dynamic equations are solved simultaneously to obtain the stage pressure at various load conditions. The details of the mathematical formulation of the model and open loop responses for specific disturbances are presented.

Regulation of several androgen-induced genes through the repression of the miR-99a/let-7c/miR-125b-2 miRNA cluster in prostate cancer cells

The androgen receptor (AR) stimulates and represses gene expression to promote the initiation and progression of prostate cancer. Here, we report that androgen represses the miR-99a/let7c/125b-2 cluster through AR and anti-androgen drugs block the androgen-repression of the miRNA cluster. AR directly binds to the host gene of the miR-99a/let7c/125b-2 cluster, LINC00478. Expression of the cluster is repressed or activated by chromatin remodelers EZH2 or JMJD3 in the presence or absence of androgen, respectively. Bioinformatics analysis reveals a significant enrichment of targets of miR-99a, let-7c and miR-125b in androgen-induced gene sets, suggesting that downregulation of the miR-99a/let7c/125b-2 cluster by androgen protects many of their target mRNAs from degradation and indirectly assists in the gene induction. We validated the hypothesis with 12 potential targets of the miR-99a/let7c/125b-2 cluster induced by androgen: 9 out of the 12 mRNAs are downregulated by the microRNA cluster. To ascertain the biological significance of this hypothesis, we focused on IGF1R, a known prostate cancer growth factor that is induced by androgen and directly targeted by the miR-99a/let7c/125b-2 cluster. The androgen-induced cell proliferation is ameliorated to a similar extent as anti-androgen drugs by preventing the repression of the microRNAs or induction of IGF1R in androgen-dependent prostate cancer cells. Expression of a microRNA-resistant form of IGF1R protects these cells from inhibition by the miR-99a/let7c/125b-2 cluster. These results indicate that a thorough understanding of how androgen stimulates prostate cancer growth requires not only an understanding of genes directly induced/repressed by AR, but also of genes indirectly induced by AR through the repression of key microRNAs.

Initial experience with lingual mucosal graft urethroplasty for anterior urethral strictures

BACKGROUND

To present the feasibility of lingual mucosal graft urethroplasty in anterior urethral strictures and appraisal of donor site morbidity.

METHODS

From November 2007 to December 2010, 14 patients underwent dorsal onlay lingual mucosal graft urethroplasty for anterior urethral strictures. Lingual mucosal graft was harvested from the lateral and undersurface of the tongue. Check micturating cystourethrograms were done 2 weeks after catheter removal and uroflowmetry after 3 months. Success was defined as normal uroflowmetry rates at 3 months in the absence of any postoperative instrumentation. Tongue was assessed for any residual pain, taste disturbances or restricted movement at 3 months.

RESULTS

Four patients had submucosal fibrosis of the oral cavity and their buccal mucosa was unfit for grafting. Mean (range) stricture length was 5 (3-16) cm and the operation time 170 (140-210) min. Graft width averaged 1.6 cm. Average length of harvested graft was 6.5 cm. Mean duration of follow-up was 12.8 months. Two patients developed stricture at the proximal anastomotic site. There were no donor site complications.

CONCLUSIONS

Lingual mucosal graft harvesting is simple, gives graft lengths comparable to buccal mucosa and is associated with negligible donor site morbidity.

Study of the effects of chemotherapy on auditory function

Chemotherapeutic agents are known to cause multiple toxicities such as myelotoxicity, nephrotoxicity and ototoxicity. A prospective study was carried out on 60 patients receiving Cisplatin based chemotherapy in a tertiary care centre. The effects of Cisplatin on auditory function were studied using metabolic, biochemical and audiological parameters. The auditory effects were correlated with the dose and duration of chemotherapy. The study concluded that a significant percentage (15%) of patients who were subjected to chemotherapy based on Cisplatin developed high frequency sensorineural hearing loss which was permanent and irreversible in nature.

Bioavailability, antioxidant and non toxic properties of a radioprotective formulation prepared from isolated compounds of Podophyllum hexandrum: a study in mouse model

The current study was aimed to determine the stability, serum protein binding ability, biodistribution, antioxidant potential and tissue toxicity status of a novel radioprotective formulation (G-002M) from Podophyllum hexandrum. G-002M is the combination of a flavonoid, a lignan and its glucoside isolated from P. hexandrum rhizome that exhibit high radioprotective potential. Stability of G-002M tagged with 99mTc was observed in vitro and with mice serum till 24 hr of incubation. The formulation was investigated for its antioxidant status and its bioavailability and toxicity in different organs of mice. Biodistribution study of 99mTc-G-002M revealed its uptake by all the vital organs of mice. Higher absorbed dose was observed in lungs, liver, jejunum and kidney. Maximum retention of G-002M in kidney revealed that G-002M was excreted predominantly through renal route. G-002M was also observed to have high free radical scavenging and total reducing properties. Histopathological observations showed no significant alterations in tissue morphology of lungs, liver, jejunum and kidney by G-002M administration. The data conclusively demonstrate that high stability, multi organ availability, longer retention and non-toxic behavior of G-002M might help in exhibiting strong protective potential against lethal radiation.

CFD analysis of a hydraulic valve for cavitating flow

A successful design of high pressure hydraulic valves requires a thorough analysis of both velocity and pressure fields, with the aim of improving the geometry to avoid cavitation. Cavitation behavior prediction of hydraulic valves and its associated performance drop is of high interest for the manufacturers and for the users. The paper presents a CFD analysis of the flow inside a high pressure hydraulic valve. First, the analysis was carried out without using cavitation model (single phase). It was observed that absolute pressure was going below the vapor pressure. Hence, it was required to turn on the cavitation model. This model enables formation of vapor from liquid when the pressure drops below the vaporization pressure. Since the cavitation bubble grows in a liquid at low temperature, the latent heat of evaporation can be neglected and the system can be considered isothermal. Under these conditions the pressure inside the bubble remains practically constant and the growth of the bubble radius can be approximated by the simplified Rayleigh equation. For typical poppet valve geometry, ½ of computational domain is assumed, with pressure inlet and outlet boundary conditions, and a steady flow solution is computed. Because of the highly complex geometry of the hydraulic valve, the computational domain was meshed using unstructured grids using tetrahedral cells only. The paper presents a numerical investigation of the flow inside a hydraulic valve using commercial CFD code CFD-ACE. The aim of the study is to provide a good basis for future designing of the hydraulic valve. The result indicated the cavitation zones which in turn suggest needs of modification of present geometry.