Electromagnetic levitation containerless processing of metallic materials in microgravity: rapid solidification.

Space levitation processing allows researchers to conduct benchmark tests in an effort to understand the physical phenomena involved in rapid solidification processing, including alloy thermodynamics, nucleation and growth, heat and mass transfer, solid/liquid interface dynamics, macro- and microstructural evolution, and defect formation. Supported by ground-based investigations, a major thrust is to develop and refine robust computational tools based on theoretical and applied approaches. This work is accomplished in conjunction with experiments designed for precise model validation with application to a broad range of industrial processes.

Quantum mechanical interpretation of the minimum viscosity of metallic liquids.

Possible fundamental quantum bounds for viscosity and many other physical properties have drawn serious considerations recently from diverse communities encompassing those studying quantum gravity, high-energy physics, condensed matter physics, strongly correlated electron systems, and "strange metals," to name a few. However, little attention has been paid by materials scientists and the fluid dynamics community, perhaps because of the general belief that quantum mechanics is of little consequence for classical fluid dynamics. Here, considering the extrapolated high-temperature viscosity of 32 metallic alloy liquids as representative of minimum viscosity, experimental results are presented and evaluated in terms of a number of quantum- and statistical-mechanics-based theories. The surprising result is that the experimental data are within one order of magnitude of estimates from those theories. That quantum mechanics could be of importance at such high temperatures in conventional classical fluids is quite interesting. Another surprise is that the minimum viscosities of metallic alloy liquids are not too different from an archetypal quantum liquid, such as He.

Salvage surgery for recurrent carcinoma of the oral cavity: assessment of prognostic factors.

Salvage surgery is the most acceptable therapeutic option for disease control of loco-regional recurrences in oral cancers. Prognostic factors need to be assessed to select patients for salvage surgery who would benefit the most. This was a single-centre retrospective observational study conducted between 2015 and 2018. A total of 168 patients with recurrent oral cavity carcinoma who underwent salvage surgery were included for analysis. The primary endpoints of the study were to evaluate overall survival (rOS) after salvage surgery and prognostic factors affecting survival. In this study, the median rOS was 18 months and the median disease-free survival (rDFS) was 14 months. Advanced stage (hazard ratio (HR) 2.387, 95% confidence interval (CI) 1.496-3.808; P = 0.001) and multimodality treatment (HR 1.642, 95% CI 1.139-2.367; P = 0.008) in the initial disease, as well as nodal spread (HR 3.794, 95% CI 1.580-9.111; P = 0.008) and perineural invasion (HR 2.167, 95% CI 1.358-3.455; P = 0.001) in the recurrent disease, were found to adversely affect survival after salvage surgery. With thorough assessment of the prognostic factors and appropriate patient selection, survival may be favourable after salvage surgery for recurrent oral cavity carcinoma.

Demonstration of the effect of stirring on nucleation from experiments on the International Space Station using the ISS-EML facility.

The effect of fluid flow on crystal nucleation in supercooled liquids is not well understood. The variable density and temperature gradients in the liquid make it difficult to study this under terrestrial gravity conditions. Nucleation experiments were therefore made in a microgravity environment using the Electromagnetic Levitation Facility on the International Space Station on a bulk glass-forming Zr57Cu15.4Ni12.6Al10Nb5 (Vit106), as well as Cu50Zr50 and the quasicrystal-forming Ti39.5Zr39.5Ni21 liquids. The maximum supercooling temperatures for each alloy were measured as a function of controlled stirring by applying various combinations of radio-frequency positioner and heater voltages to the water-cooled copper coils. The flow patterns were simulated from the known parameters for the coil and the levitated samples. The maximum nucleation temperatures increased systematically with increased fluid flow in the liquids for Vit106, but stayed nearly unchanged for the other two. These results are consistent with the predictions from the Coupled-Flux model for nucleation.

Resistivity Saturation in Metallic Liquids Above a Dynamical Crossover Temperature Observed in Measurements Aboard the International Space Station.

Although a resistivity saturation (minimum conductivity) is often observed in disordered metallic solids, such phenomena in the corresponding liquids are not known. Here we report a saturation of the electrical resistivity in Zr_{64}Ni_{36} and Cu_{50}Zr_{50} liquids above a dynamical crossover temperature for the viscosity (T_{A}). The measurements were made for the levitated liquids under the microgravity conditions of the International Space Station. Based on recent molecular dynamics simulations, the saturation is likely due to the ineffectiveness of electron-phonon scattering above T_{A} when the phonon lifetime becomes too short compared to the electron relaxation time. This is different from the conventional resistivity saturation mechanisms in solids.

Maximum supercooling studies in Ti39.5Zr39.5Ni21, Ti40Zr30Ni30, and Zr80Pt20 liquids-Connecting liquid structure and the nucleation barrier.

Almost three quarters of a century ago, Charles Frank proposed that the deep supercooling observed in metallic liquids is due to icosahedral short-range order (ISRO), which is incompatible with the long-range order of crystal phases. Some evidence in support of this hypothesis had been published previously. However, those studies were based on a small population of maximum supercooling measurements before the onset of crystallization. Here, the results of a systematic statistical study of several hundred maximum supercooling measurements on Ti39.5Zr39.5Ni21, Ti40Zr30Ni30, and Zr80Pt20 liquids are presented. Previous X-Ray and neutron scattering studies have shown that the structures of these liquid alloys contain significant amounts of ISRO. The results presented here show a small work of critical cluster formation (W* = 31-40 kBT) from the analysis of the supercooling data for the Ti39.5Zr39.5Ni21 liquid, which crystallizes to a metastable icosahedral quasicrystal. A much larger value (W* = 54-79 kBT and W* = 60-99 kBT) was obtained for the Ti40Zr30Ni30 and Zr80Pt20 liquids, respectively, which do not crystallize to an icosahedral quasicrystal. Taken together, these results significantly strengthen the validity of Frank's hypothesis.

Consensus on the Management of Posterior Urethral Valves from Antenatal Period to Puberty.

The need for successful management of posterior urethral valves always captivates the minds of pediatric surgeons. Its success, however, depends on several factors ranging from prenatal preservation of upper tracts to postoperative pharmacological compliance. Regardless of measures available, some cases do not respond and progress to end stage. The management depends on several issues ranging from age and severity at presentation to long-term follow-up and prevention of secondary renal damage and managing valve bladder syndrome. This article is based on a consensus to the set of questionnaires, prepared by research section of Indian Association of Paediatric Surgeons and discussed by experienced pediatric surgeons based in different institutions in the country. Standard operating procedures for conducting a voiding cystourethrogram and cystoscopy were formulated. Age-wise contrast dosage was calculated for ready reference. Current evidence from literature was also reviewed and included to complete the topic.

A re-evaluation of thermal expansion measurements of metallic liquids and glasses from x-ray scattering experiments.

Previous studies reported a number of anomalies when estimates of linear thermal expansion coefficients of metallic liquids and glasses from x-ray scattering experiments were compared with direct measurements of volume/length changes with temperature. In most cases, the first peak of the pair correlation function showed a contraction, while the structure factor showed an expansion, but both at rates much different from those expected from the direct volume measurements. In addition, the relationship between atomic volume and the characteristic lengths obtained from the structure factor from scattering experiments was found to have a fractional exponent instead of one equal to three, as expected from the Ehrenfest relation. This has led to the speculation that the atomic packing in liquids and glasses follow a fractal behavior. These issues are revisited in this study using more in-depth analysis of recent higher resolution data and some new ideas suggested in the literature. The main conclusion is that for metallic alloys, at least to a large extent, most of these anomalies arise from complicated interplays of the temperature dependences of the various partial structure factors, which contribute to the total intensities of the scattering peaks.

Correlation of the fragility of metallic liquids with the high temperature structure, volume, and cohesive energy.

The thermal expansion coefficients, structure factors, and viscosities of twenty-five equilibrium and supercooled metallic liquids have been measured using an electrostatic levitation (ESL) facility. The structure factor was measured at the Advanced Photon Source, Argonne, using the ESL. A clear connection between liquid fragility and structural and volumetric changes at high temperatures is established; the observed changes are larger for the more fragile liquids. It is also demonstrated that the fragility of metallic liquids is determined to a large extent by the cohesive energy and is, therefore, predictable. These results are expected to provide useful guidance in the future design of metallic glasses.

Tension pneumoperitoneum: a very rare complication of acute gangrenous appendicitis.

Tension pneumoperitoneum is a very rare consequence of acute gangrenous appendicitis. We report a case of a 32-year-old woman who presented with abdominal pain, progressively increasing abdominal distension, profound hemodynamic instability and ventilatory compromise. The diagnosis of tension pneumoperitoneum was confirmed by computed tomography, which showed compression of the intra-abdominal viscera and liver (saddlebag sign) by a large volume of intraperitoneal free air. Urgent needle decompression was done as an emergency measure. Exploratory laparotomy, planned due to persistent peritonitis, revealed gangrenous appendicitis with perforation near its base. Appendicectomy with excision of gangrenous portion of caecum was performed. The purpose of the reporting this case is to highlight that the tension pneumoperitoneum can be, very rarely, associated with gangrenous appendicitis and timely diagnosis is very important for the emergency management of this deadly condition.

Respiratory Distress Secondary to Rhabdomyosarcoma of the Tongue and Co-existent Choanal Atresia.

Whilst rhabdomyosarcoma (RMS) is the third most common solid tumour in children, congenital RMS of the tongue is extremely rare and usually present as painless progressive mass since birth (Dagher and Helman in Oncologist 4:34-44, 1999; Childs and Goudy in Int J Pediatr Otorhinolaryngol 5:126-128, 2010). In neonates, presentation with respiratory distress is unexpected as neonates are preferential nasal breathers and restricted oral breathing due to tumour usually poses no problem. We herein report a case of rhabdomyosarcoma of the tongue with co-existent unilateral choanal atresia, presenting with respiratory distress. The baby developed upper respiratory tract infection following which developed severe respiratory distress. Airway symptoms were precipitated as there was combined obstruction of both the nostrils due to infection or adenoid enlargement and unilateral chonal atresia. Treatment of respiratory distress in the presence of RMS and bilateral nasal pathology must first prioritise the security of the airway, before taking a multi-factorial approach to the therapy of the lingual mass (Childs and Goudy in Int J Pediatr Otorhinolaryngol 5:126-128, 2010). This case illustrates the importance of vigilance with respect to co-existent nasal pathology, in order to avoid the occurrence of complete airway obstruction. We therefore feel that any diagnosis of lingual RMS should warrant a formal examination of both nasal cavities.

Traumatic abdominal wall hernia with concealed colonic perforation.

Traumatic abdominal wall hernia (TAWH) is a rare clinical entity in terms of aetiology. It occurs following a blunt abdominal injury with energy high enough to cause disruption of the musculoaponeurotic layer but not the elastic skin layer. It is often associated with underlying intra-abdominal injuries, which can be diagnosed either clinically or radiologically. We report a case of TAWH in a young man with associated large bowel transection, which remained undiagnosed in the preoperative period owing to its masked features. He was managed surgically, with no recurrence to date. Considering the high volume of blunt abdominal trauma cases that present to the accident and emergency department, only few cases of TAWH have been reported in the literature. Confusion still exists regarding the timing and mode of management of this condition.

Assessment and comparison of fecal continence in children following primary posterior sagittal anorectoplasty and abdominoperineal pull through for anorectal anomaly using clinical scoring and MRI.

INTRODUCTION: We aimed to compare and contrast these main surgical procedures for ARM in terms of structural outcome through pelvic MRI & functional outcome through Kelly's scoring. MATERIAL AND METHOD: A prospective study was conducted from August 2011 to July 2013 including all the cases of ARM managed in single stage (operated by one surgeon, first author) since 1995 that came for follow up at age of 3 years or more. Patients were divided in three groups: Group 8.A, PSARP (60 patients); Group B, Abdomino-PSARP (40 patients); and Group C, APPT (40 patients). The functional assessment of anal continence was carried out at the age of 3years or more using Kelly's method. Structural assessment was done by 1.5-T Magnetic Resonance Imaging (MRI). RESULTS: In 24 patients with rectobulbar fistula, 71.5% of Group A patients had good continence. In 50 patients with rectoprostatic fistula, 73.7% of Group A, 70% of group B and only 36% of Group C had good outcomes. Better development of each muscle was associated with better outcomes in terms of anal continence (P=0.001). CONCLUSION: There is better outcome with PSARP and Abdomino-PSARP in patients with rectobulbar and rectoprostatic fistula. MRI is a valuable modality for postoperative structural analysis of patients with ARM and is also useful for predicting the long term functional outcome of these cases.

Fish/flaxseed oil protect against nitric oxide-induced hepatotoxicity and cell death in the rat liver.

Sodium nitroprusside (SNP) is an antihypertensive drug with proven toxic effects attributed mainly to the production of nitric oxide (NO). Polyunsaturated fatty acids (PUFAs) are widely regarded as functional foods and have been shown to ameliorate the harmful effects of many toxicants. This study examined whether feeding of fish oil (FO)/flaxseed oil (FXO) would have any protective effect against SNP-induced hepatotoxicity and cell death. Male Wistar rats were fed either on normal diet or with 15% FO/FXO for 15 days, following which SNP (1.5 mg/kg body weight) was administered intraperitoneally for 7 days. Animals were killed after treatment, and livers were collected for further analysis. We observed that SNP significantly elevated tissue nitrite levels and lipid peroxidation (LPO) with concomitant perturbation in antioxidant defense systems accompanied with dysregulated glucose metabolism and pronounced cellular death. FO/FXO supplementation to SNP-treated rats caused reversal of tissue injury/cell death and markedly decreased LPO and improved antioxidant defense systems. FO/FXO appear to protect against SNP-induced hepatotoxicity by improving energy metabolism and antioxidant defense mechanism.

In Vitro Evaluation of Carbachol and Endothelin on Contractility of Colonic Smooth Muscle in Hirschsprung's Disease.

Background: The hypomotility of colon observed in Hirschsprung's disease (HD) has been attributed to congenital aganglionosis only. So far, it is not clear whether the contractility of colonic smooth muscle in this condition is altered or not. Therefore, the present study attempted to understand the contractile status of colonic segments of HD patients by examining carbachol and endothelin (ET-1) evoked colonic smooth muscle contractions in vitro . Methods: Contractile responses were recorded from strips of colonic segments obtained from HD patients, using organ bath preparations. Cholinergic agonist carbachol and ET-1 along with their antagonists were used to evoke contractile responses. Thereafter, the samples were histopathologically confirmed for HD. Results: Colonic strips of HD did not show any spontaneous contractions but responded to carbachol and ET-1 to a lesser extent. In HD, response of carbachol was blocked by atropine and hexamethonium by nearly 73% and 50% respectively. ET-1 induced contractile responses were blocked by ET-A and ET-B antagonist up to 40%, signifying the possible role of ET-A and ET-B receptors in HD colon contractility. Conclusion: As evidenced by lack of spontaneous contractions and impaired carbachol and ET-1-induced contractile responses, it is concluded that, in addition to aganglionosis, decreased contractility of colonic smooth muscle may contribute to hypomotility observed in patients with HD.

Estimation of pro-renin as a prognostic marker for renal function in PUV patients.

OBJECTIVE: To estimate serum pro-renin, and its clinical significance, as a marker of chronic renal disease in posterior urethral valve (PUV) patients. PATIENTS AND METHODS: Forty patients with a PUV that were admitted to the hospital between 2010 and 2012 were reviewed. Twenty age-matched patients who were admitted for other non-urological diseases were selected for control. Clinical parameters, serum creatinine, urea, eGFR (estimated glomerular filtration rate) and serum pro-renin were analysed before and after valve ablation. RESULTS: Forty patients with PUV were included in the study. Three groups were formed according to age: <1 year, 1-3 years, >3 years. Pro-renin was measured using an ELISA (enzyme linked immunosorbent assay) kit and 'Graph Pad Prism' Software. The Spearman's rho test was used for correlation. Serum pro-renin had a negative correlation with the age group (correlation coefficient -0.395, P-value 0.012), eGFR (correlation coefficient -0.850, P-value<0.001) and follow-up eGFR (correlation coefficient -0.471, P-value 0.002). The pro-renin level correlated positively with serum creatinine at presentation (correlation coefficient 0.671, P-value<0.001), blood urea at initial presentation (correlation coefficient 0.684, P-value<0.001), serum creatinine at follow-up (correlation coefficient 0.546, P-value<0.001) and blood urea at follow-up (correlation 0.603, P-value<0.001). CONCLUSION: Pro-renin measured before PUV repair is associated with renal function three months after surgery.

Assessment of phenol infiltration resilience in soil media by HYDRUS-1D transport model for a waste discharge site.

The movement of contaminants through soil imparts a variety of geo-environmental problem inclusive of lithospheric pollution. Near-surface aquifers are often vulnerable to contamination from surface source if overlying soil possesses poor resilience or contaminant attenuation capacity. The prediction of contaminant transport through soil is urged to protect groundwater from sources of pollutants. Using field simulation through column experiments and mathematical modeling like HYDRUS-1D, assessment of soil resilience and movement of contaminants through the subsurface to reach aquifers can be predicted. An outfall site of effluents of a coke oven plant comprising of alarming concentration of phenol (4-12.2 mg/L) have been considered for studying groundwater condition and quality, in situ soil characterization, and effluent characterization. Hydrogeological feature suggests the presence of near-surface aquifers at the effluent discharge site. Analysis of groundwater of nearby locality reveals the phenol concentration (0.11-0.75 mg/L) exceeded the prescribed limit of WHO specification (0.002 mg/L). The in situ soil, used in column experiment, possess higher saturated hydraulic conductivity (KS = 5.25 × 10(-4) cm/s). The soil containing 47 % silt, 11 % clay, and 1.54% organic carbon content was found to be a poor absorber of phenol (24 mg/kg). The linear phenol adsorption isotherm model showed the best fit (R(2) = 0.977, RMSE = 1.057) to the test results. Column experiments revealed that the phenol removal percent and the length of the mass transfer zone increased with increasing bed heights. The overall phenol adsorption efficiency was found to be 42-49%. Breakthrough curves (BTCs) predicted by HYDRUS-1D model appears to be close fitting with the BTCs derived from the column experiments. The phenol BTC predicted by the HYDRUS-1D model for 1.2 m depth subsurface soil, i.e., up to the depth of groundwater in the study area, showed that the exhaustion point was reached within 12 days of elapsed time. This clearly demonstrated poor attenuation capacity of the soil to retard migration of phenol to the groundwater from the surface outfall site. Suitable liner, based on these data, may be designed to inhibit subsurface transport of phenol and thereby to protect precious groundwater from contamination.

Neonatal necrotising fasciitis managed conservatively: an experience from a tertiary centre.

OBJECTIVE: Conventional therapy for neonatal necrotising fasciitis (NF) involves resuscitation and aggressive surgical debridement of necrotic tissue. This approach adds surgical stress in septicaemic neonates with low reserves. The present study reports a more conservative approach to the management of neonatal NF. METHOD: A prospective study was conducted between July 2010 and June 2013 and included 11 cases of neonatal NF. Demographic characteristics of patients were noted. No debridement was performed. Dressings were applied after cleaning with normal saline every 24 hours. The necrotic slough was allowed to separate spontaneously. A record was made of type and duration of supportive modalities and complications. The primary outcome was recorded as final recovery, need of surgical intervention or need of grafting. RESULTS: Out of 11 neonates, 6 were males and 5 were females. Age ranged from 13 to 24 days (mean age 18.45±3.24 days), and weight varied from 1.8 to 2.6 kg (mean weight 2.12±0.24kg) at presentation. Duration of illness before admission to hospital ranged from 3 to 9 days (mean 4.84±2.13 days). The most common site of the initial involvement was the neck and upper thoracic region (n=4), scalp (n=3), lower back (n=2), face (n=1) and extremities (n=1). In all cases, the wound was cleaned with normal saline, dressed, necrotic slough was allowed to separate spontaneously and granulation tissue was allowed to develop; this took approximately 14 to 28 days (mean 20.45±5.78 days). CONCLUSION: As opposed to the conventional approach of aggressive debridement in neonatal NF, these cases can be managed conservatively without increase in morbidity or mortality. This approach also minimises the surgical risk and requirement of blood transfusion. Antifungal drugs have a definitive role in management of these immunologically deficient babies.