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We present an experimental and numerical investigation of electrokinetic instability (EKI) in microchannel flow with streamwise conductivity gradients, such as those observed during sample stacking in capillary electrophoresis. A plug of a low-conductivity electrolyte solution is initially sandwiched between two high-conductivity zones in a microchannel. This spatial conductivity gradient is subjected to an external electric field applied along the microchannel axis, and for sufficiently strong electric fields an instability sets in. We have explored the physics of this EKI through experiments and numerical simulations, and supplemented the results using scaling analysis. We performed EKI experiments at different electric field values and visualised the flow using a passive fluorescent tracer. The experimental data were analysed using the proper orthogonal decomposition technique to obtain a quantitative measure of the threshold electric field for the onset of instability, along with the corresponding coherent structures. To elucidate the physical mechanism underlying the instability, we performed high-resolution numerical simulations of ion transport coupled with fluid flow driven by the electric body force. Simulations reveal that the non-uniform electroosmotic flow due to axially varying conductivity field causes a recirculating flow within the low-conductivity region, and creates a new configuration wherein the local conductivity gradients are orthogonal to the applied electric field. This configuration leads to EKI above a threshold electric field. The spatial features of the instability predicted by the simulations and the threshold electric field are in good agreement with the experimental observations and provide useful insight into the underlying mechanism of instability.
The aim of this paper is to introduce a new stochastic order based on the residual lifetimes of two nonnegative dependent random variables and the stochastic precedence order. We develop some characterizations and preservation properties of this stochastic order. In addition, we study some of its reliability properties and its relation with other existing stochastic orders. One of the possible applications in reliability theory has also been discussed.
Resistance to colistin, a last resort antibiotic, has emerged in India. We investigated colistin-resistant Klebsiella pneumoniae(ColR-KP) in a hospital in India to describe infections, characterize resistance of isolates, compare concordance of detection methods, and identify transmission events.
Retrospective observational study.
Case-patients were defined as individuals from whom ColR-KP was isolated from a clinical specimen between January 2016 and October 2017. Isolates resistant to colistin by Vitek 2 were confirmed by broth microdilution (BMD). Isolates underwent colistin susceptibility testing by disk diffusion and whole-genome sequencing. Medical records were reviewed.
Of 846 K. pneumoniae isolates, 34 (4%) were colistin resistant. In total, 22 case-patients were identified. Most (90%) were male; their median age was 33 years. Half were transferred from another hospital; 45% died. Case-patients were admitted for a median of 14 days before detection of ColR-KP. Also, 7 case-patients (32%) received colistin before detection of ColR-KP. All isolates were resistant to carbapenems and susceptible to tigecycline. Isolates resistant to colistin by Vitek 2 were also resistant by BMD; 2 ColR-KP isolates were resistant by disk diffusion. Moreover, 8 multilocus sequence types were identified. Isolates were negative for mobile colistin resistance (mcr) genes. Based on sequencing analysis, in-hospital transmission may have occurred with 8 case-patients (38%).
Multiple infections caused by highly resistant, mcr-negative ColR-KP with substantial mortality were identified. Disk diffusion correlated poorly with Vitek 2 and BMD for detection of ColR-KP. Sequencing indicated multiple importation and in-hospital transmission events. Enhanced detection for ColR-KP may be warranted in India.
A trauma registry is a disease-specific data collection composed of a file of uniform data elements that describe the injury even, demographics, prehospital information, diagnosis, care, outcomes, and costs of treatment for injured patients.
To establish a trauma registry system on an electronic platform enabling data capturing through Android phones.
A software has been developed for the registry data collection for road traffic injury patients arriving at JPNATC, AIIMS, New Delhi. The software has been designed to use in the Emergency Department on Android phones/laptops with internet access.
A detailed registry data set has been prepared to enter prehospital, in-hospital, and post-discharge details of all the admitted patients. This includes demographic data, prehospital data, injury event data, vital signs within 24-hrs of arrival, ED disposition (date and time), operative procedures within 48 hours of arrival, chest x-ray (date and time), CT (date and time), ventilation days, ICU-stay days, hospital disposition (date and time), injury coding data (region, severity level, ISS, AIS, ICD-10) and Others, e.g., first neurosurgical consultation (date and time) and first blood transfusion (date and time). There are two panels for this software; one for user panel and another for the administrative panel. User panel is being used for data collection by the trained data collectors 24/7 at the emergency department on a rotation basis. The administrative panel is accessible to only the investigator or other authorized persons. The administrative panel and user panels are password protected. The entered data is being saved in a spreadsheet in the backend and can be used for periodic data quality check and data analysis.
There is no trauma registry in India so far for the road traffic injury patients. Present innovation would lay the foundation of national Trauma Registry in India.
Indian railway systems are fourth largest in the world, and cause on average 15 deaths daily due to various intentional and unintentional reasons. This study presents a 5-year retrospective data analysis of polytrauma patients with train-related injuries.
To highlight key lessons learned from data analysis to inform better safety measures and laws.
Trauma registry data between 2012 and 2016 were analyzed for patients with train-related injuries. Data from 726 patients were analyzed for demographics, event, injuries, management, and final outcome. ISS was used to quantify the extent of injury.
Mean patient age was 33 years with an 86% to 14% male to female ratio. 62% of patients were in the 20- to 40-year age group. Average time of arrival at health facility post-injury was 3.3 hours. Half of the patients were trespassers. Mean ISS was 11.65. Chest injuries were present in 24.6% of patients, with half requiring interventions like ICD insertion or surgery. 20% of patients underwent amputations of extremities. 40% of patients needed admission to the ICU. 3.5% died in the Emergency Department (ED). Mean hospital stay was 17 days with an in-hospital mortality of 17.4%.
This analysis is the largest to date showing comprehensive injury patterns and outcomes of train-related injuries from a developing country. Patients injured on the platform and off the platform had the same severity of injuries. This analysis shows the need for safety measures and strict law enforcement both at the station and at the track.
In the present work, the effect of cooling rate on the evolution of the microstructure and mechanical properties of an α + β titanium alloy has been systematically investigated. Titanium alloy samples were heated to 1066 °C (above the β transus), 930 °C (just below the β transus), and 850 °C (well below the β transus) followed by oil quenching, air cooling, and furnace cooling, respectively. Primary alpha (αp), lamellar alpha (αL), and martensite (α′) were the dominant features of the microstructures for all the samples heated below the β transus. Furnace-cooled samples showed variation in the size and shape of the αp and fraction of αL according to the heating temperature. At slower cooling rates, the thickness of the αL increased with the increase in temperature. Transmission electron microscopy and X-ray diffraction confirmed the presence of α′ in all the quenched samples. The volume fraction and size of the αp decreased with the increase in temperature but was independent of the cooling rate. The microhardness was relatively unaffected by the cooling rate for heating just below the β transus, i.e., 930 °C. The modulus of elasticity was found to be extremely sensitive to the microstructure.
The objective of the study was to identify incidence, aetiology, and outcomes of extubation failure in infants with shunt-dependent pulmonary blood flow at a single tertiary care, academic children's hospital. The second objective of this study was to determine the haemodynamic effects of transition of positive pressure ventilation to spontaneous breathing in infants with extubation failure.
Patients and methods
Extubation failure for our study was defined as the need for positive pressure ventilation within 96 hours after extubation. We collected demographics, pre-operative, intra-operative, post-operative, and peri-extubation data in a retrospective, observational format in patients who underwent a modified Blalock–Taussig shunt between January, 2005 and March, 2011. Infants undergoing Norwood operation or Damus–Kaye–Stansel with modified Blalock–Taussig shunt were excluded from the study. The cardiorespiratory variables collected before extubation and immediately after extubation included heart rate, respiratory rate, mean arterial blood pressure, central venous pressures, near infrared spectroscopy, oxygen saturations, and lactate levels. Clinical outcomes evaluated included the success or failure of extubation, cardiovascular intensive care unit length of stay, hospital length of stay, and mortality. Descriptive and univariate statistics were utilised to compare groups with extubation failure and extubation success.
Of the 55 eligible patients during the study period, extubation failure occurred in 27% (15/55) of the patients. Of the 15 patients with extubation failure, 10 patients needed reintubation and five patients received continuous positive pressure ventilation without getting reintubated. There were three patients who had extubation failure in the first 2 hours after extubation, nine patients in the 2–24-hour period, and three patients in the 24–96-hour period. In all, eight patients were extubated in the second attempt after the first extubation failure, with a median duration of mechanical ventilation of 2 days (1 day, 6 days). The median age of patients at extubation was 19 days (12 days, 22 days) and median weight of patients was 3.6 kg (3.02 kg, 4.26 kg). In all, 38% (21/55) of the patients were intubated before surgery. The most common risk factors for failed extubation were lung disease in 46% (7/15), cardiac dysfunction in 26% (4/15), diaphragmatic paralysis in 13% (2/15), airway oedema in 6% (1/15), and vocal cord paralysis in 6% (1/15). The median duration of mechanical ventilation was 4 days (1 day, 10.5 days), median cardiovascular intensive care unit length of stay was 11 days (6.5 days, 23.5 days), and the median hospital length of stay was 30 days (14 days, 48 days). The overall mortality at the time of hospital discharge was 7%.
Extubation failure in infants with shunt-dependent pulmonary blood flow and univentricular physiology is high and aetiology is diverse. Cardiopulmonary effects of removal of positive pressure ventilation are more pronounced in children with extubation failure and include escalation in the need for oxygen requirement and increase in mean arterial blood pressure. The majority of extubation failures in this select patient population occurs in the first 24 hours. Extubation failure in these patients is not associated with increased hospital length of stay or mortality.
A before-after prospective surveillance study to assess the impact of a multidimensional infection control approach for the reduction of catheter-associated urinary tract infection (CAUTI) rates.
Pediatric intensive care units (PICUs) of hospital members of the International Nosocomial Infection Control Consortium (INICC) from 10 cities of the following 6 developing countries: Colombia, El Salvador, India, Mexico, Philippines, and Turkey.
We performed a prospective active surveillance to determine rates of CAUTI among 3,877 patients hospitalized in 10 PICUs for a total of 27,345 bed-days. The study was divided into a baseline period (phase 1) and an intervention period (phase 2). In phase 1, surveillance was performed without the implementation of the multidimensional approach. In phase 2, we implemented a multidimensional infection control approach that included outcome surveillance, process surveillance, feedback on CAUTI rates, feedback on performance, education, and a bundle of preventive measures. The rates of CAUTI obtained in phase 1 were compared with the rates obtained in phase 2, after interventions were implemented.
During the study period, we recorded 8,513 urinary catheter (UC) days, including 1,513 UC-days in phase 1 and 7,000 UC-days in phase 2. In phase 1, the CAUTI rate was 5.9 cases per 1,000 UC-days, and in phase 2, after implementing the multidimensional infection control approach for CAUTI prevention, the rate of CAUTI decreased to 2.6 cases per 1,000 UC-days (relative risk, 0.43 [95% confidence interval, 0.21–1.0]), indicating a rate reduction of 57%.
Our findings demonstrated that implementing a multidimensional infection control approach is associated with a significant reduction in the CAUTI rate of PICUs in developing countries.
A two-dimensional lattice Boltzmann model has been employed to simulate the impingement of a liquid drop on a dry surface. For a range of Weber number, Reynolds number and low density ratios, multiple phases leading to breakup have been obtained. An analytical solution for breakup as function of Reynolds and Weber number based on the conservation of energy is shown to match well with the simulations. At the moment breakup occurs, the spread diameter is maximum; it increases with Weber number and reaches an asymptotic value at a density ratio of 10. Droplet breakup is found to be more viable for the case when the wall is non-wetting or neutral as compared to a wetting surface. Upon breakup, the distance between the daughter droplets is much higher for the case with a non-wetting wall, which illustrates the role of the surface interactions in the outcome of the impact.
The aim of the present study was to determine the impact of universal salt iodization (USI) on the prevalence of iodine deficiency in the population of an area previously known to have severe iodine deficiency in India.
In a cross-sectional survey, a total of 2860 subjects residing in fifty-three villages of four sub-districts of Gonda District were examined for goitre and urinary iodine concentration. Free thyroxine and thyroid-stimulating hormone levels were also measured. Salt samples from households were collected for estimation of iodine content.
A reduction in goitre prevalence was observed from 69 % reported in 1982 to 27·7 % assessed in 2007. However, 34 % of villages still had very high endemicity of goitre (goitre prevalence >30 %). Twenty-three per cent of households consumed a negligible amount (<5 ppm) and 56 % of households consumed an insufficient amount (5–15 ppm) of iodine from salt.
Although there was an overall improvement in iodine nutrition as revealed by decreased goitre prevalence and increased median urinary iodine levels, there were several pockets of severe deficiency that require a more targeted approach. Poor coverage, the use of unpackaged crystal salt with inadequate iodine and the washing of salt before use by 90 % of rural households are the major causes of persisting iodine-deficiency disorders. This demonstrates lapses in USI implementation, lack of monitoring and the need to identify hot spots. We advocate strengthening the USI programme with a mass education component, the supply of adequately iodized salt and the implementation of complementary strategies for vulnerable groups, particularly neonates and lactating mothers.
Rhinosporidiosis is a granulomatous infection usually affecting the nasal mucosa and conjunctiva. The disease is widely prevalent in India and Sri Lanka. Tracheo-bronchial involvement is extremely rare and is potentially life threatening. Diagnosis of tracheal involvement is a challenge due to the risk of bleeding during attempted bronchoscopic biopsy.
A 73-year-old man was admitted with severe respiratory distress, for which emergency tracheostomy was performed. At tracheostomy, a fleshy mass was seen emerging from the wound. Pathological examination of the mass confirmed rhinosporidiosis involving the trachea. Complete excision of the mass was performed after initial stabilisation of the patient.
Tracheo-bronchial rhinosporidiosis, a rare complication of nasopharyngeal infection, should be considered in a known case presenting with severe respiratory distress.
A novel combination of depth-sensing nano-indentation, micro-indentation and micro-FTIR techniques is employed towards understanding the durability of coating layers used on engineering thermoplastics upon exposure to harsh weathering environments. This combination of techniques enables study of changes in surface-to-bulk properties in the clearcoat-substrate system upon weathering; typically observed as a degradation starting from the surface and then proceeding inwards to the bulk of the material. Nano-indentation measurements carried out to understand the mechanical properties of the coating layer provide insights into the changes in hardness and modulus upon prolonged weathering exposure. Depth-sensing micro-indentation and micro-FTIR spectroscopy studies performed to evaluate mechanical performance and chemical changes, respectively, explain the influence of the substrate on the coating layer, especially at the interface upon weathering. This unique combination of depth-sensing indentation and micro-FTIR spectroscopy has led to an understanding of the properties of the coating layer and the substrate individually as well as an integral system as a function of weathering exposure time. Finally, the physico-chemical properties of the coating and substrate are linked to performance prediction, enabling optimization of coating-substrate combinations.
The purpose of this paper is to report on our work to develop a real-time monitoring device by using micro-cantilevers for the mass detection of biological organisms in air and fluid. The biological agent used was Bacillus anthracis Sterne spore. The experiment was conducted using a laser Doppler vibrometer (LDV) to measure the resonant frequency of the thermal noise cantilevers and the corresponding decrease in frequency as a result of the added mass. Moreover, the added mass attributed to the spores was quantified and compared in air and deionized (DI) water. The silicon cantilevers used in this study were of lengths ranging from 25 μm to 50 μm, 200 nm thick and a width of approximately 9 μm. The first part of the experiment consisted of suspending spores onto the cantilevers in fluid, drying the cantilevers, performing measurements in air and extracting the mass of the added spores. The average mass of a spore in air was 367 fg. The second part of the experiment utilized antibody and bovine serum albumin (BSA) physically adsorbed onto the cantilevers in order to fix the spores on the surface during the measurements in deionized water. The extracted mass of a spore in fluid was measured to be an average of 1.85 pg. This study demonstrated the ability to detect biological samples not only in air but also in a liquid environment.
A process was developed for patterning thin films of environmentally sensitive hydrogels onto silicon microcantilevers. Microcantilevers have been shown to be ultra-sensitive transducers for chemical, physical, and biological microsensors. By patterning environmentally sensitive hydrogels onto silicon microcantilevers, novel microsensors were prepared for MEMS and BioMEMS applications. Specifically, a cross-linked poly(methacrylic acid) (PMAA) network containing significant amounts of poly(ethylene glycol) dimethacrylate (PEGDMA) was studied. This hydrogel exhibits a swelling dependence on pH. By increasing the environmental pH above the pKa of PMAA to cause ionization of the carboxylic acid groups, electrostatic repulsion is produced along the main polymer chain causing the polymer network to expand and swell. Therefore, a pH change induces swelling or shrinking of the polymer network and creates stress on the microcantilever surface causing it to bend. In this study, silicon microcantilevers were fabricated on p-type (100) SOI wafers. Covalent adhesion was gained between the polymer and the silicon surface through the modification of the silicon surface with γ-methacryloxypropyl trimethoxysilane. Hydrogels were patterned onto the silicon microcantilevers utilizing a mask aligner to allow for precise positioning. The micropatterned hydrogels were analyzed using optical microscopy and profilometry. The bending response of patterned cantilevers with a change in environmental pH was observed, providing proof-of-concept for a MEMS/BioMEMS sensor based on microcantilevers patterned with environmentally sensitive hydrogels.