Precise determination of plutonium in nuclear fuel process samples.

A REDOX-based analytical method was developed for determining the plutonium concentration. In this method, plutonium was oxidized to the +6-oxidation state using of ceric ammonium nitrate solution. The interference from ceric(IV) nitrate was suppressed by reducing its oxidation state from +4 to +3 with sodium nitrite. Hexavalent plutonium in this sample was then reduced to be tetravalent by adding a known volume of excess standard ferrous ammonium sulphate. The dichromate equivalence required for unreacted ferrous ammonium sulphate was determined to obtain the concentration of plutonium. Interference studies from chemicals envisaged to be present in the PUREX process stream, such as dissolved tri-n-butyl phosphate, uranium, and various reagents employed during analysis, were performed for the determination of plutonium concentration. The relative standard deviation was found and it is within ± 1.0% for an aliquot containing plutonium in a range of 0.7-2.5 mg.

Asymptomatic central line-associated bloodstream infections in children implanted with long term indwelling central venous catheters in a teaching hospital, Sri Lanka.

BACKGROUND: Indwelling central venous catheters (CVC) are used to provide long term hemodialysis. The commonest and the severe complication of CVC is the central line-associated bloodstream infection (CLABSI). This study was done to assess the etiology and infectious complications of CVC in children on long term hemodialysis. METHODS: Children newly undergoing hemodialysis and having indwelling CVC were included. They were followed up to a period of 2-years to assess infectious complications. Catheter bundle care approach was employed to prevent infections and other complications. Automated culture from the central catheter and peripheral vein and 2D echocardiography were done in each hemodialysis. Serial procalcitonin (PCT) was measured. Differential time of positivity (DTP) was used to detect CLABSI. During homestay in weekly telephone conversations were done to assess features of infection, and whenever having, we have asked to admit to the tertiary care unit. Logistic regression was performed, and the significant outcome variable was considered following multivariable analysis as a risk factor. RESULTS: Blood cultures were positive in 1090 (74.5%) out of 1462 children. According to DTP, 410 (28%) were having CLABSI, while 520 (35.6%) were having bacteremia without CLABSI. Out of 410 CLABSI patients, 79 (19.2%) were asymptomatic. Coagulase-negative Staphylococcus spp. (CoNS) bacteremia was significantly associated with asymptomatic CLABSI. Right-sided infective endocarditis (RS-IE) was significantly associated with asymptomatic CLABSI and asymptomatic bacteremia without CLABSI. CoNS was associated significantly in RS-IE following asymptomatic CLABSI and asymptomatic bacteremia. PCT was in asymptomatic CLABSI was 1.8 ± 0.9 ng/mL while in symptomatic CLABSI was 11.3 ± 2.5 ng/ml (P = 0.02). CoNS bloodstream infection, tunneled CVC, peripherally inserted central catheter, femoral site, the number of line days > 90, receipt of vancomycin, meropenem, or linezolid in the 5 days before CLABSI diagnosis and recurrent bacteremia were risk factors for asymptomatic CLABSI. CONCLUSIONS: Asymptomatic CLABSI could be a rare occurrence. CoNS was predominantly isolated in patients with asymptomatic CLABSI. RS- IE is a well-known complication in long term indwelling CVC. CoNS was significantly associated with RS-IE following asymptomatic CLABSI. Regular procalcitonin, microbiological, and imaging studies would be essential to detect infectious complications in both symptomatic and asymptomatic patients implanted with long term indwelling CVCs.

Comparative Evaluation of Bone Formation between PRF and Blood Clot Alone as the Sole Sinus-Filling Material in Maxillary Sinus Augmentation with the Implant as a Tent Pole: A Randomized Split-Mouth Study.

The lack of bone volume in the posterior maxillary region can be augmented with sinus elevation. Since the elevated sinus is a closed cavity, a blood clot that fills the sinus space itself can aid in bone formation. The aim of this study was to compare bone formation in the elevated maxillary sinus between platelet-rich fibrin (PRF) and blood clot alone as the sole sinus-filling material with the implant as a tent pole. The study was a randomized controlled trial with a split-mouth design involving seven patients. An implant was placed on one side only and blood was allowed to fill the elevated sinus cavity; on the other side, PRF plugs were inserted. The sinus window was covered by nonresorbable titanium-reinforced membrane. The results showed that there was no statistically significant difference between the two groups, but the PRF group showed increased bone gain in the mesial, buccal, and palatal regions, and increased average height and bucco-palatal width at the height of the old and new sinus floor. A greater increase in distal bone height was seen in the control group. It was concluded that PRF may be more effective as a sole sinus-filling material in the elevated sinus cavity with an implant as a tent pole.

Maximum Spreading of Liquid Drops Impacting on Groove-Textured Surfaces: Effect of Surface Texture.

Maximum spreading of liquid drops impacting on solid surfaces textured with unidirectional parallel grooves is studied for drop Weber number in the range 1-100 focusing on the role of texture geometry and wettability. The maximum spread factor of impacting drops measured perpendicular to grooves, ßm,⊥ is seen to be less than that measured parallel to grooves, ßm,∥. The difference between ßm,⊥ and ßm,∥ increases with drop impact velocity. This deviation of ßm,⊥ from ßm,∥ is analyzed by considering the possible mechanisms, corresponding to experimental observations-(1) impregnation of drop into the grooves, (2) convex shape of liquid-vapor interface near contact line at maximum spreading, and (3) contact line pinning of spreading drop at the pillar edges-by incorporating them into an energy conservation-based model. The analysis reveals that contact line pinning offers a physically meaningful justification of the observed deviation of ßm,⊥ from ßm,∥ compared to other possible candidates. A unified model, incorporating all the above-mentioned mechanisms, is formulated, which predicts ßm,⊥ on several groove-textured surfaces made of intrinsically hydrophilic and hydrophobic materials with an average error of 8.3%. The effect of groove-texture geometrical parameters on maximum drop spreading is explained using this unified model. A special case of the unified model, with contact line pinning absent, predicts ßm,∥ with an average error of 6.3%.

A survey on investigating the need for intelligent power-aware load balanced routing protocols for handling critical links in MANETs.

In mobile ad hoc networks connectivity is always an issue of concern. Due to dynamism in the behavior of mobile nodes, efficiency shall be achieved only with the assumption of good network infrastructure. Presence of critical links results in deterioration which should be detected in advance to retain the prevailing communication setup. This paper discusses a short survey on the specialized algorithms and protocols related to energy efficient load balancing for critical link detection in the recent literature. This paper also suggests a machine learning based hybrid power-aware approach for handling critical nodes via load balancing.

Transition from Cassie to impaled state during drop impact on groove-textured solid surfaces.

Liquid drops impacted on textured surfaces undergo a transition from the Cassie state characterized by the presence of air pockets inside the roughness valleys below the drop to an impaled state with at least one of the roughness valleys filled with drop liquid. This occurs when the drop impact velocity exceeds a particular value referred to as the critical impact velocity. The present study investigates such a transition process during water drop impact on surfaces textured with unidirectional parallel grooves referred to as groove-textured surfaces. The process of liquid impalement into a groove in the vicinity of drop impact through de-pinning of the three-phase contact line (TPCL) beneath the drop as well as the critical impact velocity were identified experimentally from high speed video recordings of water drop impact on six different groove-textured surfaces made from intrinsically hydrophilic (stainless steel) as well as intrinsically hydrophobic (PDMS and rough aluminum) materials. The surface energy of various 2-D configurations of liquid-vapor interface beneath the drop near the drop impact point was theoretically investigated to identify the locally stable configurations and establish a pathway for the liquid impalement process. A force balance analysis performed on the liquid-vapor interface configuration just prior to TPCL de-pinning provided an expression for the critical drop impact velocity, Uo,cr, beyond which the drop state transitions from the Cassie to an impaled state. The theoretical model predicts that Uo,cr increases with the increase in pillar side angle, α, and intrinsic hydrophobicity whereas it decreases with the increase in groove top width, w, of the groove-textured surface. The quantitative predictions of the theoretical model were found to show good agreement with the experimental measurements of Uo,cr plotted against the surface texture geometry factor in our model, {tan(α/2)/w}(0.5).

Directional motion of impacting drops on dual-textured surfaces.

In this work, we analyze the directional movement of impacting liquid drops on dual-textured solid surfaces comprising two different surface morphologies: a textured surface and a smooth surface. The dynamics of liquid drops impacting onto the junction line between the two parts of the dual-textured surfaces is studied experimentally for varying drop impact velocity. The dual-textured surfaces used here featured a variation in their textures' geometrical parameters as well as their surface chemistry. Two types of liquid drop differing in their surface tension were used. The impact process develops a net horizontal drop velocity towards the higher-wettability surface portion and results in a bulk movement of the impacting drop liquid. The final distance moved by the impacting drop from the junction line decreases with increasing impacting drop Weber number We. A fully theoretical model, employing a balance of forces acting at the drop contact line as well as energy conservation, is formulated to determine the variation, with We, of net horizontal drop velocity and subsequent movement of the impacting drop on the dual-textured surfaces.

Modulation of peristalsis by NK3 receptor antagonism in guinea-pig isolated ileum is revealed as intraluminal pressure is raised.

1. NK(3) tachykinin receptors mediate slow excitatory transmission in the enteric nervous system and play a role in reflexes induced by the intestinal stretch or mucosal compression. However, there is little evidence to suggest that these receptors are important in peristalsis. We have examined the effects of the NK(3) receptor antagonist, talnetant, on peristalsis in guinea-pig isolated ileum induced by optimal and by supra-maximal distension pressures. 2. At the guinea-pig NK(3) receptor, talnetant was shown to have high affinity (pK(B) 8.8) and selectivity over the guinea-pig NK(1) and NK(2) receptors. 3. Peristaltic waves in the ileum elicited by optimal distension pressures (1-3 cmH(2)O) were unaffected by talnetant at a supra-maximal concentration (250 nm). 4. Distension at a higher pressure (4 cmH(2)O) induced peristalsis in which there was incomplete closure of the lumen during each peristaltic wave and an increase in the periods of inactivity observed between bursts of peristaltic activity. The addition of talnetant (250 nm) increased the number of peristaltic events by reducing these periods of inactivity and thus, increased the productivity of the peristaltic reflex. 5. The data suggest that NK(3) receptors are not involved in the modulation of peristaltic movements by physiological stimuli, but they may have a role in modulation of reflexes in extreme or pathological conditions.

Altered structure and expression of RB1 gene and increased phosphorylation of pRb in human vestibular schwannomas.

Tumor-specific alterations at the RB1 gene locus in 30 human vestibular schwannomas including 10 NF2 and 20 sporadic cases were analysed. Southern blot analysis of DNA from these samples revealed loss of heterozygosity (LOH) at the RB1 locus in 6 of 24 informative cases (25%) compared to normal blood DNAs from the same patients. Northern blot analysis showed normal size RB1 mRNA in all the tumor samples. However, there was a 2-5-fold increase in the level of expression of the RB1 gene in all the tumor samples compared to the WI38 cell line which was used as control. Western blot analysis of the RB1 protein, pRb showed a 2.5-5-fold increase in the level of total pRb as compared to normal WI38 cell line. Sixty five to seventy five percent of the total pRb were in phosphorylated form in most tumors. The LOH at the RB1 gene locus suggests genetic instability in these patients. Further, increased levels of RB1 mRNA, total pRb and the phosphorylated form of pRb suggests that RB1 gene in these tumors may have anti-apoptotic function. These results suggest that the RB1 gene has a major role in the development of human vestibular schwannomas.

Early Disappearance of Cord Signal Changes Following Endovascular Treatment of a Spinal Dural AV Fistula.

SUMMARY: Spinal dural arterio venous fistulas (SDAVFs) are the commonest type of spinal vascular malformations and are encountered mostly among adult patients. Magnetic Resonance Imaging (MRI) in patients with SDAVFs demonstrates features like spinal cord swelling and signal changes. Cord signal changes are believed to be due to venous stasis.Treatment of a spinal vascular malformation may result in complete or partial resolution of MR findings with associated clinical improvement. The earliest documentation of reduction or disappearance of cord signal changes on post treatment MR images, was one month later in one series in the literature.We present and discuss disappearance of cord signal changes on MRI within 72 hours following endovascular treatment by liquid glue injection in a patient with SDAVF.

Bronchodilator delivered by metered dose inhaler and spacer improves respiratory system compliance more than nebulizer-delivered bronchodilator in ventilated premature infants.

We compared the change in passive respiratory system compliance (Crs) and resistance (Rrs) after albuterol aerosol treatment administered by either low-flow nebulizer (NEB) or a metered dose inhaler (MDI) and spacer into a ventilator circuit. We hypothesized that albuterol delivered to ventilated infants older than 7 days of life by an MDI and a spacer would improve Crs more than albuterol delivered by a low-flow nebulizer. The treatments were administered 6 hr apart to premature infants with Crs < or = 0.8 mL/cm H2O per kg, requiring ventilation after 7 days of age. Patients served as their own controls and treatment order was randomized. Eighteen studies were performed in eight infants before and 1 and 3 hr after treatment. Differences between methods were compared by analyses of variance. Mean (range) birth weight and study age were 888 (619-1,283) g and 12 (7-29) days, respectively. Mean respiratory system compliance increased by 34% with MDI and by 11% with NEB at 1 hr after treatment (P < 0.02). By 3 hr after treatment, Crs returned to baseline with both methods of aerosol delivery. There was no significant difference in Rrs between the two methods at 1 and 3 hr after treatment. We conclude that albuterol delivered by MDI improves Crs more than low-flow NEB in ventilated premature infants.