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.

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.

Anomalous thermal contraction of the first coordination shell in metallic alloy liquids.

Except for a few anomalous solids and liquids, materials expand upon heating. For liquids, this should be reflected as a shift in the peak positions in the pair correlation function, g(r), to higher r. Here, we present the results of a detailed study of the volume thermal expansion coefficients and the temperature dependences of g(r) for a large number of binary, ternary, and quaternary liquids in the equilibrium and supercooled (metastable liquid below the liquidus temperature) states. The data were obtained from x-ray scattering and volume measurements on levitated liquids using the electrostatic levitation technique. Although the volumes of all liquids expand with increasing temperature, the peak positions in g(r) for the first coordination shells contract for the majority of alloy liquids studied. The second and third peaks in g(r) expand, but at rates different from those expected from the volume expansion. This behavior is explained qualitatively in terms of changes in the coordination numbers and bond-lengths as clusters in liquids break up with increasing temperature.

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.

Non-operative management of giant omphalocele with topical povidone-iodine and powdered antibiotic combination: early experience from a tertiary centre.

PURPOSE: The aim of the study was to evaluate topical povidone-iodine and topical powdered antibiotic combination (Polymyxin, Bacitracin and Neomycin) in initial non-operative management with delayed closure of the defect of giant omphaloceles. METHODS: A prospective study was conducted between July 2010 and June 2013 including all neonates with giant omphalocele without signs of intestinal obstruction. All cases were managed by daily application of povidone-iodine (5% solution) followed by spraying topical powdered antibiotic combination to promote eschar formation and eventual epithelialisation. Record was made of sex, associated anomalies, length of stay, and thyroid function tests. RESULTS: Twenty-four neonates with giant omphaloceles were treated with topical povidone-iodine and topical powdered antibiotic combination. No sac ruptures were observed in our series. All patients had a normal thyroid function test at presentation and after 10 days of initiation of treatment. Six patients have undergone delayed repair. CONCLUSION: Topical povidone-iodine and powdered antibiotic combination promotes more rapid escharification and epithelialisation of the omphalocele than povidone-iodine alone. We also hypothesise that combination minimises the chances of hypothyroidism associated with use of povidone-iodine alone.

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.

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.

Volume expansion measurements in metallic liquids and their relation to fragility and glass forming ability: an energy landscape interpretation.

Recent studies of Cu-Zr glasses have reported a rapid variation in the amorphous phase density near the optimal glass forming compositions, supporting the belief that the densest liquids are also the best glass formers. Here, we show that the measured densities of the Cu-Zr liquids at higher temperatures are not peaked sharply near these compositions, but the volume expansivities are. Theoretical studies have shown that the expansivity correlates with fragility near T(g); the experimental results presented here show that at high temperature they become anticorrelated. From energy landscape arguments, this indicates the existence of a crossover temperature for the expansivity-fragility correlation that scales inversely with the liquid fragility. These results lead to an improved understanding of the high temperature properties of liquids that form glasses and suggest a new method for identifying the best glass forming compositions within an alloy system from the properties of the equilibrium liquids.

Self-organized bimetallic Ag-Co nanoparticles with tunable localized surface plasmons showing high environmental stability and sensitivity.

We demonstrate a promising synthesis route based on pulsed laser dewetting of bilayer films (Ag and Co) to make bimetallic nanoparticle arrays. By combining experiment and theory we establish a parameter space for the independent control of composition and diameter for the bimetallic nanoparticles. As a result, physical properties, such as the localized surface plasmon resonance (LSPR), that depend on particle size and composition can be readily tuned over a wavelength range one order of magnitude greater than for pure Ag nanoparticles. The LSPR detection sensitivity of the bimetallic nanoparticles with narrow size distribution was found to be high-comparable with pure Ag (∼60 nm/RIU). Moreover, they showed significantly higher long-term environmental stability over pure Ag.

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.

Unusual content of omphalocele: a congenital mature cystic teratoma of falciform ligament of the liver.

Omphalocele is a congenital midline abdominal wall defect that results in herniation of intraabdominal contents covered by a lining of peritoneum and amnion. The severity of the defect often ranges from a minor herniation of the umbilical cord to a significant protrusion that includes large proportions of intestine and liver. We report unusual content of omphalocele that is congenital mature cystic teratoma of falciform ligament of liver which was confirmed by histopathology. This is a very uncommon entity and not described in world literature.

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.

A study of the functional aberration of the pouch in anorectal malformation associated with congenital pouch colon.

OBJECTIVE: There are no in vitro studies of congenital pouch colon (CPC) associated with anorectal malformation (ARM) to understand its mechanism of contractility. There is no consensus regarding the utilization of the CPC in repair of anorectal malformation. In view of the above, it was decided to carry out detailed in vitro physiological study of the excised CPC. METHOD: The excised specimens of CPC were taken and 15- to 20-mm long both longitudinal and transverse strips of muscle were obtained both from the proximal and distal part. Contraction was recorded using software chart-5 for windows. Drugs used were acetylcholine, histamine, adrenaline, atropine and pheniramine maleate. The amplitude of contractions was converted to tension gram and then the tension so developed was expressed as tension per unit mass (per gram of wet tissue). RESULTS: There were total of 21 specimens of high ARM with CPC. Five specimens were of the complete pouch, which did not show a response to any drug and the remaining 16 had an incomplete pouch. The mean longitudinal and circular muscle contractions of these 16 samples were statistically higher for the proximal segment than the distal segment both for acetylcholine and histamine. The effect of atropine was not significant but that of adrenaline and pheniramine maleate were significant on the distal segment muscle. CONCLUSION: Congenital pouch colon being deficient or having poorly developed receptors in their wall can not function properly as a reservoir for faeces and, hence, it should be excised to allow adequate function.

Chronic bilious vomiting in children in developing countries due to high bowel obstruction: not always malrotation or tuberculosis.

BACKGROUND: Bilious vomiting, in conjunction with abdominal pain is considered to be a surgical problem, unless proved otherwise. In children, besides tuberculosis (TB), we have found jejunal stricture (JS) due to non-specific jejunoileitis (NSJI) to be an important cause of chronic high small bowel obstruction and bilious vomiting. MATERIALS AND METHODS: In this retrospective study, the records of all children with complaint of intermittent bilious vomiting and failure to thrive were evaluated. Investigations included oral contrast study, ultrasound abdomen, chest X-ray and Mantoux test. Final confirmation was made at laparotomy. Treatment included jejuno-jejunal resection and anastomosis. Histopathology of the specimen was done to look for caseation, granuloma formation and other details. RESULTS: Out of total 100 patients with the complaint of bilious vomiting, 25 were having JS. Radiologic confirmation was possible in 19 (76%) patients of JS. No patient had evidence of TB as per our protocol. Histopathology revealed non-specific ischemic changes in all specimens. CONCLUSION: Jejunal stricture due to NSJI is a common entity in our setup leading to bilious vomiting. Contrast study can provide high index of suspicion in most of the patients. The diagnosis must be confirmed after proper histopathological examination. The results of the surgery are excellent.