Microscale heterogeneous pore occupancy with variable background resistance.

Fluid flow through porous media often involves the spontaneous displacement of one immiscible fluid by another. On the level of adjacent channels, a pore doublet model can estimate the relative flow rates in the two channels and the final fluid occupancy of the pair. Pore doublet models nominally capture the dominant roles of capillarity and viscosity, by describing the flow using hydraulic circuit theory. However, this approach neglects the more complex fluid flow in the region where the immiscible fluids meet, and therefore the applicability of this model for low aspect-ratio pores commonly seen in natural media is questionable. We show that for large channel aspect ratios, the numerical results replicate the traditional pore doublet models; however, as the aspect ratio approaches unity, the accuracy of these models break down. We quantify the effect of complex flow on the final fluid occupancy, which we link to the excess energy dissipation rate from the flow near the immiscible interface. Our results indicate that a minimal 1D pore doublet model may be sufficient to model global dynamics, including the fraction of residual oil that remains trapped in a reservoir, where the pore diameter and length are comparable.

Enhanced oil displacement by nanofluid's structural disjoining pressure in model fractured porous media.

Nanofluids for improved oil recovery has been demonstrated through laboratory corefloods. Despite numerous experimental studies, little is known about the efficacy of nanofluids in fractured systems. Here, we present studies of nanofluid injection in fractured porous media (both water-wet and oil-wet) formed by sintering borosilicate glass-beads around a dissolvable substrate. The fracture inside the porous medium is characterized and visualized using a high resolution X-ray microtomography. Based on a simple displacement theory, the nanofluid injection is conducted at a rate where structural disjoining pressure driven oil recovery is operational. An additional 23.8% oil was displaced using nanofluid after brine injection with an overall recovery efficiency of 90.4% provided the matrix was in its native wettability state. But only 6% additional oil was displaced by nanofluid following brine injection when the bead-pack was rendered oil-wet. Nanofluids appear to be a good candidate for enhanced oil recovery (EOR) in fractured water-wet to weakly water-wet media but not necessarily for strongly oil-wet systems. Our laboratory studies enable us to understand limitations of nanofluids for improving oil recovery in fractured media.

Primary Tubercular Abscess of the Axilla-a Rare Case.

Tuberculosis can be broadly classified as pulmonary and extrapulmonary. Though pulmonary tuberculosis is the most common presentation, extrapulmonary tuberculosis is also an important entity. A tubercular cold abscess secondary to involvement of an adjacent bone or suppuration of lymph nodes is a well-known entity; however, a primary cold abscess is rare. We report a case of a young girl who presented with an axillary swelling which turned out to be a primary tubercular abscess of the axilla. To the best of our knowledge, this is the first reported case of a primary tubercular abscess presenting in the axilla. A primary tubercular abscess, though rare, should be considered as a possible diagnosis in appropriate clinical settings backed by evidence of Mycobacterium tuberculosis in form of AFB microscopy, L-J culture, BACTEC culture, or PCR test.

Necrotizing Fasciitis: A Rare Complication of Acute Necrotizing Pancreatitis.

Necrotizing pancreatitis occurs in 10 to 25% of patients requiring hospital admission for acute pancreatitis and carries a high mortality rate. Necrotizing pancreatitis can cause a spectrum of complications. However, we report an extremely rare complication of necrotizing pancreatitis: necrotizing fasciitis of the abdominal wall. A 56-year-old male patient presented to our center with discoloration of skin over left flank of 15 days duration and pus discharge from it since three days. Two months back he was managed at a private hospital as a case of acute necrotizing pancreatitis and was discharged after one week of inpatient treatment. After discharge patient continued to have malaise and weakness but was able to do his routine day to day activity. On presentation at our hospital, patient was in septic shock and was taken emergently to operating theatre for debridement. However, later, the patient succumbed to his illness. Necrotizing fasciitis is an extremely uncommon complication of necrotizing pancreatitis and has a fulminant course. Timely detection and debridement can avert a potential mortality.

Measurement of off-diagonal transport coefficients in two-phase flow in porous media.

The prevalent description of low capillary number two-phase flow in porous media relies on the independence of phase transport. An extended Darcy's law with a saturation dependent effective permeability is used for each phase. The driving force for each phase is given by its pressure gradient and the body force. This diagonally dominant form neglects momentum transfer from one phase to the other. Numerical and analytical modeling in regular geometries have however shown that while this approximation is simple and acceptable in some cases, many practical problems require inclusion of momentum transfer across the interface. Its inclusion leads to a generalized form of extended Darcy's law in which both the diagonal relative permeabilities and the off-diagonal terms depend not only on saturation but also on the viscosity ratio. Analogous to application of thermodynamics to dynamical systems, any of the extended forms of Darcy's law assumes quasi-static interfaces of fluids for describing displacement problems. Despite the importance of the permeability coefficients in oil recovery, soil moisture transport, contaminant removal, etc., direct measurements to infer the magnitude of the off-diagonal coefficients have been lacking. The published data based on cocurrent and countercurrent displacement experiments are necessarily indirect. In this paper, we propose a null experiment to measure the off-diagonal term directly. For a given non-wetting phase pressure-gradient, the null method is based on measuring a counter pressure drop in the wetting phase required to maintain a zero flux. The ratio of the off-diagonal coefficient to the wetting phase diagonal coefficient (relative permeability) may then be determined. The apparatus is described in detail, along with the results obtained. We demonstrate the validity of the experimental results and conclude the paper by comparing experimental data to numerical simulation.

Primary cervical thoracic duct cyst: a case report and review of the literature.

Thoracic duct cysts are uncommon entities that are usually found in the thoracic segments of the thoracic duct. The presence of a thoracic duct cyst in the cervical area has been rarely reported. Etiologically, these cysts can arise either as a primary growth or secondary to trauma, obstruction, or inflammation. This entity was first described in 1964, and only 33 cases have been previously reported in literature. Of these, 16 cases involved a primary cyst. We report a new case of a primary thoracic duct cyst, and we discuss its presentation, diagnosis, and management, with an emphasis on meticulous surgical technique. We also review the relevant literature.

Relative permeability experiments of carbon dioxide displacing brine and their implications for carbon sequestration.

To mitigate anthropogenically induced climate change and ocean acidification, net carbon dioxide emissions to the atmosphere must be reduced. One proposed option is underground CO2 disposal. Large-scale injection of CO2 into the Earth's crust requires an understanding of the multiphase flow properties of high-pressure CO2 displacing brine. We present laboratory-scale core flooding experiments designed to measure CO2 endpoint relative permeability for CO2 displacing brine at in situ pressures, salinities, and temperatures. Endpoint drainage CO2 relative permeabilities for liquid and supercritical CO2 were found to be clustered around 0.4 for both the synthetic and natural media studied. These values indicate that relative to CO2, water may not be strongly wetting the solid surface. Based on these results, CO2 injectivity will be reduced and pressure-limited reservoirs will have reduced disposal capacity, though area-limited reservoirs may have increased capacity. Future reservoir-scale modeling efforts should incorporate sensitivity to relative permeability. Assuming applicability of the experimental results to other lithologies and that the majority of reservoirs are pressure limited, geologic carbon sequestration would require approximately twice the number of wells for the same injectivity.

Spatial fluctuations of fluid velocities in flow through a three-dimensional porous medium.

We use confocal microscopy to directly visualize the spatial fluctuations in fluid flow through a three-dimensional porous medium. We find that the velocity magnitudes and the velocity components both along and transverse to the imposed flow direction are exponentially distributed, even with residual trapping of a second immiscible fluid. Moreover, we find pore-scale correlations in the flow that are determined by the geometry of the medium. Our results suggest that despite the considerable complexity of the pore space, fluid flow through it is not completely random.

Single port laparoscopic repair of paediatric inguinal hernias: Our experience at a secondary care centre.

BACKGROUND: Congenital inguinal hernias are a common paediatric surgical problem and herniotomy through a groin incision is the gold standard. Over the last 2 decades minimally invasive surgery (MIS) has challenged this conventional surgery. Over a period, MIS techniques have evolved to making it more minimally invasive - from 3 to 2 and now single port technique. All studies using single port technique are from tertiary care centres. We used a modification of the technique described by Ozgediz et al. and reviewed the clinical outcome of this novel procedure and put forth our experience at a secondary level hospital. MATERIALS AND METHODS: Prospective review of 37 hernias in 31 children (29 male and 2 female) (8 months - 13 years) performed laparoscopically by a single surgeon at a single centre between September 2007 and June 2010. Under laparoscopic guidance, the internal ring was encircled extraperitoneally using a 2-0 non-absorbable suture and knotted extraperitoneally. Data analyzed included operating time, ease of procedure, occult patent processus vaginalis (PPV), complications, and cosmesis. RESULTS: Sixteen right (52%), 14 left (45%) and 1 bilateral hernia (3%) were repaired. Five unilateral hernias (16.66%), all left, had a contralateral PPV that was repaired (P = 0.033). Mean operative time for a unilateral and bilateral repair were 13.20 (8-25) and 20.66 min (17 -27 min) respectively. Only one of the repairs (2.7%) recurred and another had a post operative hydrocoele (2.7%). One case (2.7%) needed an additional port placement due to inability to reduce the contents of hernia completely. There were no stitch abscess/granulomas, obvious spermatic cord injuries, testicular atrophy, or nerve injuries. CONCLUSION: Single port laparoscopic inguinal hernia repair can be safely done in the paediatric population. It permits extension of benefits of minimal access surgery to patients being managed at secondary level hospitals with limited resources. The advantage of minimal instrumentation and avoidance of intracorporeal knotting makes it a feasible technique for a secondary care centre.

Persistent omphalomesenteric duct causing small bowel obstruction in an adult.

We report an unusual presentation of persistent omphalomesenteric duct causing intestinal obstruction in a middle-aged adult. Exploratory laparotomy revealed persistence of omphalomesenteric duct causing terminal ileum obstruction. Meckel's diverticulum along with gangrenous segment of ileum was resected and end-to-end anastomosis was done.

Internal hernia through the descending mesocolon following left radical nephrectomy--a rare complication: case report and review of the literature.

The causes for internal hernias can be broadly classified as congenital or acquired, the latter being caused by post surgical or traumatic defects. An internal hernia following nephrectomy is a relatively rare occurrence. A nephrectomy via the transperitoneal approach has complications which are common to any abdominal surgery, as well as some which are specific to it. However, an internal hernia through the descending mesocolon is rare, and, to the best of our knowledge, very few cases have been reported in the literature. We report a case of internal hernia through the descending mesocolon following left radical nephrectomy, review the available literature on this observation and discuss its pathogenesis and prevention.

Prevalence of Early Stages of Chronic Kidney Disease in Healthy Army Personnel.

INTRODUCTION: Chronic kidney disease (CKD) is associated with significant morbidity and mortality. Screening and detection of early stages of CKD can help institute interventions that may delay the progression of the disease. One aim was to study the prevalence of early stages of CKD in the Army. METHODS: A cross-sectional study of Army Personnel in an Army cantt in Central India was carried out. All participants filled a structured questionnaire and anthropometric data was collected. Investigative profile included routine urine exam, semi-quantitative microalbuminuria (MAU), serum creatinine, lipid profile and fasting blood glucose. Glomerular Filteration rate (eGFR) was calculated using the Modification of Diet in Renal Diseases (MDRD) study equation. RESULT: A total of 1920 subjects were examined with 731 (38.07%) from Arms and 1189 (61.93%) from Services. 348 were excluded and of the remaining 1572 subjects, 141 (8.97 %) had MAU and 157 (9.99 %) had deranged Albumin Creatinine Ratio (ACR). Mean eGFR by MDRD equation was 102 ± 25.84 ml/min/1.73m (2) . Early CKD was seen in 150 (9.54 %) with 84 (5.34 %) in stage I CKD, 55 (3.5%) in stage II and 11 (0.7%) in stage III. Multiple logistic regression showed BMI > 23, the presence of DM and HTN were independent risk factors for CKD. CONCLUSION: 9.54% of healthy army personnel were found to have early stages of CKD. Institution of screening programs can result in early detection of CKD.

Prevalence of early stages of chronic kidney disease in apparently healthy central government employees in India.

BACKGROUND: Chronic kidney disease (CKD) is associated with significant morbidity and mortality. US data show that 11-15.6% of population has CKD, but there is no data from India on early stages of CKD. The aim of this study was to estimate the prevalence of early stages of CKD using the Kidney Disease Quality Outcomes Initiative (KDOQI) guidelines in an Indian population. METHODS: A cross-sectional study of Indian central government employees over 18 years of age was carried out. Data on anthropometric profile and investigations including routine urine exam, semi-quantitative microalbuminuria (MAU), serum creatinine, lipid profile and fasting blood glucose (FPG) were collected. Estimated glomerular filtration rate (eGFR) was calculated using the Modification of Diet in Renal Diseases (MDRD) and Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equations. RESULTS: A total of 3398 subjects, with 2244 (66.04%) males and 1154 (33.96%) females, were studied. Of the subjects, 9.96% (n = 284) were found to have MAU >30 mg/L, and 11.47% (n = 327) had a deranged albumin:creatinine ratio (ACR) of 30-300 mg/g. Mean GFR was 98 mL/min/1.73 m(2) (+/- 25.25) by the MDRD equation, and 100 mL/min/1.73 m(2) (+/- 19.48) by CKD-EPI. Using the MDRD equation for GFR, 189 (6.62%) had stage I CKD, 154 (5.40%) had stage II CKD and 86 (3.02%) had stage III CKD. By using the CKD-EPI equation, the corresponding percentages were 192 (6.73%), 122 (4.28%) and 60 (2.11%), respectively. Age >40 years, FPG >126 mg/dL and hypertension were found to be independent risk factors for CKD. CONCLUSIONS: Of the apparently healthy adult Indian central government employees, 15.04% and 13.12% were found to have early stages of CKD using the MDRD and CKD-EPI criteria for GFR, respectively.

Idiopathic sclerosing encapsulating peritonitis--is a preoperative diagnosis possible? Report of three cases.

Sclerosing encapsulating peritonitis (SEP) is a rare cause of intestinal obstruction that is usually diagnosed during a laparotomy; however, a preoperative diagnosis is possible. Sclerosing encapsulating peritonitis can be classified as primary or idiopathic and secondary types and only about 70 cases of idiopathic type have been reported since it was first described. It is characterized by a total or partial encasement of the small bowel by a thick fibrotic membrane. This report presents a series of three cases in which a diagnosis of idiopathic SEP was made preoperatively based on the clinical features and radiological findings, which were confirmed by a laparotomy and histopathology. All of the cases were successfully managed by the excision of the membrane. This report demonstrates that based on the clinical features and radiological investigations, in the absence of other plausible etiologies for intestinal obstruction, it is possible to suspect a preoperative diagnosis of SEP, thereby preventing a "surprise" finding during a laparotomy and allowing for better management.

Unknown Poisoning Amongst Serving Personnel.

BACKGROUND: Poisoning is recognized as an important health problem in many countries of the world. There is incomplete information on poisoning accidents, which is a major problem in developing countries. METHODS: A cross-sectional analysis of hospital records of armed forces personnel admitted with a provisional diagnosis of unknown poisoning was carried out. RESULT: Unknown poisoning represented 0.25% of hospital admissions and 6584 man-hours were lost. 85% poisonings occurred at railway station and majority were food related. Average length of stay in the hospital was 14.69 days. Ten patients required intensive care and two patients were admitted to the psychiatry ward. CONCLUSION: Majority of the incidents occurred in railways, signifying the importance of health education and precaution while proceeding on leave. Since, most of the affected were young soldiers, education should start from recruiting centers. Few patients had alcohol intoxication reflecting their dependence potential and need for reinforcing prohibition on alcohol consumption during travel.