Application of Polymers for Chemical Enhanced Oil Recovery: A Review

Polymers play a significant role in enhanced oil recovery (EOR) due to their viscoelastic properties and macromolecular structure. Herein, the mechanisms of the application of polymeric materials for enhanced oil recovery are elucidated. Subsequently, the polymer types used for EOR, namely synthetic polymers and natural polymers (biopolymers), and their properties are discussed. Moreover, the numerous applications for EOR such as polymer flooding, polymer foam flooding, alkali–polymer flooding, surfactant–polymer flooding, alkali–surfactant–polymer flooding, and polymeric nanofluid flooding are appraised and evaluated. Most of the polymers exhibit pseudoplastic behavior in the presence of shear forces. The biopolymers exhibit better salt tolerance and thermal stability but are susceptible to plugging and biodegradation. As for associative synthetic polyacrylamide, several complexities are involved in unlocking its full potential. Hence, hydrolyzed polyacrylamide remains the most coveted polymer for field application of polymer floods. Finally, alkali–surfactant–polymer flooding shows good efficiency at pilot and field scales, while a recently devised polymeric nanofluid shows good potential for field application of polymer flooding for EOR.

A Modified Contact Angle Measurement Process to Suppress Oil Drop Spreading and Improve Precision

Static contact angle measurement is a widely applied method for wettability assessment. Despite its convenience, it suffers from errors induced by contact angle hysteresis, material heterogeneity, and other factors. This paper discusses the oil drop spreading phenomenon that was frequently observed during contact angle measurements. Experimental tests showed that this phenomenon is closely related to surfactants in the surrounding phase, the remaining oil on the rock surface, and oil inside the surrounding phase. A modified contact angle measurement process was proposed. In the modified method, deionized water was used as the surrounding phase, and a rock surface cleaning step was added. Subsequent measurements showed a very low chance of oil drop spreading and improved precision. A further comparison study showed that, when the surrounding phase was deionized water, the measured contact angle values tended to be closer to intermediate-wet conditions compared to the values measured in clean surfactant solutions. This difference became more significant when the surface was strongly water-wet or strongly oil-wet. As a result, the developed process has two prerequisites: that the in-situ contact angle values inside surfactant solutions are not required, and that the wettability alteration induced by the surfactant solution is irreversible.

Surfactant Adsorption Isotherms: A Review

The need to minimize surfactant adsorption on rock surfaces has been a challenge for surfactant-based, chemical-enhanced oil recovery (cEOR) techniques. Modeling of adsorption experimental data is very useful in estimating the extent of adsorption and, hence, optimizing the process. This paper presents a mini-review of surfactant adsorption isotherms, focusing on theories of adsorption and the most frequently used adsorption isotherm models. Two-step and four-region adsorption theories are well-known, with the former representing adsorption in two steps, while the latter distinguishes four regions in the adsorption isotherm. Langmuir and Freundlich are two-parameter adsorption isotherms that are widely used in cEOR studies. The Langmuir isotherm is applied to monolayer adsorption on homogeneous sites, whereas the Freundlich isotherm suites are applied to multilayer adsorption on heterogeneous sites. Some more complex adsorption isotherms are also discussed in this paper, such as Redlich-Peterson and Sips isotherms, both involve three parameters. This paper will help select and apply a suitable adsorption isotherm to experimental data.

Socioeconomic status and trends in utilization of catheter ablation in patients hospitalized with atrial fibrillation in united states

Introduction

Atrial fibrillation (AF) is the most common arrhythmia encountered in a hospital setting. However, there is little data on the relationship of socioeconomic status (SES) and the utilization of catheter ablation amongst patients admitted with AF.

Methods

The National Inpatient Sample database was queried from 2003 to 2014 using ICD 9 revised diagnosis codes to identify patients who were hospitalized with a primary diagnosis of AF. SES was determined by median household income (MHI) and divided into quartiles (0–25th, 26–50th, 51–75th, and 76–100th). Trends were analyzed using Cochran Armitage test.

Results

We analyzed 3,618,133 patients with AF that were admitted from 2003 to 2014 (median age: 72 [IQR 61 – 81], female 52.6%). Trends stratified by MHI to compare catheter ablation rates of all 12 years revealed significant differences (Figure 1). A multivariable logistic regression accounting for sociodemographic factors revealed an increasing trend of catheter ablation utilization with higher MHI (Figure 1).

Conclusion

Over a 12-year period, patients admitted to the hospital with AF with higher MHI were found to have increasing rates of catheter ablation utilization due to AF. Conversely, a decline in catheter ablation rates were noted in patients with lower MHI.

Funding Acknowledgement

Type of funding sources: None.

284 Wunderlich Syndrome - Case Report of a Surgical Emergency Due to Spontaneous Non-Traumatic Retroperitoneal Haemorrhage

A 42-year-old female with no other significant co-morbidities presented with complaints of sudden onset abdominal pain, she was in state of shock- her haemoglobin dropped drastically to 6.8g/dl from 11.8g/dl. She was resuscitated and was given blood transfusion.

CT Scan was suggestive of retroperitoneal haemorrhage due to rupture of Renal angiomyolipoma (RAML). Patient underwent selective embolization of renal artery the next day and was discharged after 3 days of post-operative stay.

Wunderlich Syndrome-is a rare condition in which spontaneous nontraumatic renal haemorrhage occurs into the subcapsular and perirenal spaces is most commonly caused due to spontaneous rupture of RAML.It is characterized by Lenk’s triad – Acute flank pain, flank mass, hypovolemic shock. Size of AML (>4 cm), prothrombotic states such as pregnancy are main causes of AML rupture. Patients are managed conservatively or with help of selective arterial embolization. Nephrectomy is last resort in a hemodynamically unstable patient or in cases of embolization failure.

When dealing with acute abdomen with haemodynamic instability in non-traumatic cases it is essential to consider possibility of Wunderlich Syndrome. Early diagnosis, availability of Interventional radiology is key to successful management and potentially avoiding a Nephrectomy.

Prevalence and Pattern of Self-medication with Alternative Medicine: Treatment-switch Analysis in Oral Submucous Fibrosis Patients

Aim

The aim of this study was to investigate prevalence and pattern of self-medication with alternative medicine (ALM) among oral submucous fibrosis (OSF) patients with emphasis on treatment-switch analysis.

Methods

A total of 115 OSF patients were recruited and subjected to scientifically validated questionnaire. Two groups were identified: S-ALM: patients who have previously received modern medicinal treatment but switched to ALM; and DN-ALM: patients who started ALM from De Novo.

Results

A total of 37 (32.18%) patients reported use of the ALM at some point of time. Twenty-five (67.56%) switched to ALM, whereas 12 (32.43%) patients used ALM from De Novo. The pattern of switching to ALM in short period was significantly prevalent in patients with advanced stages (stage III and IV) as compared to early stages (stage I and II) of OSF. Clarified butter, glycerin, and honey were the most commonly used ALM in both the groups. The most common reasons for switching to ALM were the cost of treatment (32.00%), longer duration of medicinal treatment (24.00%) and ineffectiveness of the medications (24.00%).

Conclusions

ALM usage is common in OSMF patients with significant percentage of patient switched from modern medicine to ALM. Therapeutic efficacy of ALM in OSF needs exploration in future.

Recurrent endometrial carcinoma metastasis to the temporal bone and skull base

A 62-year old woman presented with a 1-month history of left otalgia, facial palsy and hearing loss. She had a background of non-insulin-dependent diabetes mellitus and stage 2 endometrial adenocarcinoma, treated 18 months ago. Computed tomography scan showed erosion of the skull base and temporal bone. She was referred to the otolaryngology team with a diagnosis of necrotising otitis externa. On clinical examination, there was an exophytic, necrotic lesion in the ear canal arising from the posterior canal wall. A subsequent magnetic resonance imaging scan showed a lesion located in the left jugular foramen extending into the middle ear, with characteristics consistent with a glomus jugulo-tympanicum. Interestingly, histology of the lesion showed malignant cells with immunohistochemical staining suggestive of an adenocarcinoma. This is the first reported case of metastatic endometrial carcinoma involving the jugular foramen and temporal bone. Although a diagnosis is rare, it is important to consider it when other differential diagnoses are not fitting. Imaging should always be interpreted with caution, correlating to the clinical findings.

Effect of Different Weighting Agents on Drilling Fluids and Filter Cake Properties in Sandstone Formations

Weighting agents such as barite, micromax, ilmenite, and hematite are commonly added to drilling fluids to produce high-density fluids that could be used to drill deep oil and gas wells. Increasing the drilling fluid density leads to highly conspicuous fluctuation in the drilling fluid characteristics. In this study, the variation in the drilling fluid's rheological and filtration properties induced by adding different weighting agents was evaluated. For this purpose, several water-based drilling fluid samples were prepared and weighted up using the same concentration of various weighting materials including barite, micromax, ilmenite, and hematite. The characteristics of the used weighting agents' (particle size distribution and mineralogy) were measured. Subsequently, the rheological properties of the drilling fluid were obtained using a Fann viscometer at 80 °F. The filtration test was carried out at 200 °F and 300 psi differential pressure to form a filter cake over the sandstone core samples. The properties of the formed filter cake layer such as thickness, porosity, and permeability were determined. Furthermore, the typical properties of core samples including porosity and permeability were assessed before and after the filtration test. The displayed results confirmed that the plastic viscosity (PV), yield point (YP), and filter cake sealing properties were all significantly influenced by the ratio of the large to fine particle size (D90/D10) of the weighting agents irrespective of the weighting material type. Among the examined weighting agents, barite showed novel potency to control both rheological and filter cake properties for 14 ppg drilling fluid. The results showed that D90/D10 is a key factor for the PV and YP properties as increasing the D90/D10 ratio caused PV increase and YP decrease, which indicated that the interaction among the loaded weighting materials in the drilling fluid dominated its viscosity.

Effect of prosthetic framework material, cantilever length and opposing arch on peri-implant strain in an all-on-four implant prostheses

Aim

To evaluate the effect of prosthetic framework material and cantilever length on peri-implant strain in mandibular all-on-four implant-supported prostheses with different types of arch antagonist forces.

Materials and Methods

Models simulating a completely edentulous mandibular arch fabricated in heat-cured acrylic resin were used. On the acrylic models, four implants were placed at regions 34, 32, 42, and 44 simulating all-on-four implant placements. Implant-supported screw-retained fixed prosthesis frameworks were fabricated using three different materials (cobalt-chromium, zirconia, and polyetheretherketone) and with three different cantilever lengths (zero mm, 15 mm, and 25 mm). Strain gauges were attached on the model at the buccal and lingual positions of each implant. Forces simulating opposing natural dentition, conventional complete denture, and the parafunctional habit were applied to the models. The peri-implant strain in each strain gauge was recorded.

Results

Least peri-implant strains (67 microstrains) were observed when forces simulating conventional complete dentures were applied on the models and the highest peri-implant strains (9091 microstrains) were observed when forces simulating parafunctional habit were applied. One-way ANOVA test followed by Tukey's post hoc analysis was performed to compare the mean deformation scores between different materials at 50 N load. The level of significance [P-value] was set at P < 0.05. Tests showed significant differences between zero mm and the other types in all the different materials, and also between 1.5 x AP and 2.5 x AP for Zirconia and Peek material at P = 0.02 & P = .008, respectively. The results showed that the type of framework material, cantilever length, and occlusal forces from the opposing arch influence the peri-implant strain in the bone in all-on-four implant-supported prostheses.

Conclusion

Rehabilitation of a single, completely edentulous arch with implant-supported prostheses should consider the situation of the opposing arch. The choice of framework material, as well as the cantilever length, should be altered based on the forces from the opposing arch.

Triple-negative breast cancers with expression of glucocorticoid receptor in immune cells show better prognosis

Background

Glucocorticoid receptor (GR) is shown to have variable frequency of expression in invasive tumors of the breast. Investigation of additional nuclear receptors like GR in receptor negative tumors like triple negative breast cancer (TNBC) may have prognostic and therapeutic significance.

Methods

Expression of GR was evaluated by immunohistochemistry in 175 tumors of invasive breast cancer with long term follow up. GR Expression was separately evaluated in invasive tumor cells, stromal cells and tumor infiltrating lymphocytes (TIL's). Staining pattern was categorised as positive when more than 1% of the cells stained in each subpopulation of cells. Disease free survival was analysed between GR positive and negative status by Kaplan Meier analysis.

Results

Of the 175 tumors, 121 (70%) were ER positive, 53 (30%) were ER negative and 29% (51) were triple negative. 74% (130/175) tumors showed expression of GR in invasive tumor cells while (84%) 147/175 had expression in TIL's. No significant difference in distribution of GR was noted between ER positive and ER negative tumors (78% vs 66%, p-0.1). Of the TNBC's 54% (28/51) and 70% (36/51) showed expression of GR in invasive tumor and TIL's respectively. Overall, GR positive tumors had significant better survival than GR negative tumors (mean survival time of 85 vs 59 months respectively, p-0.04) Contrary to the reports that GR expression in TIL's are associated with immunosuppressive activity in model systems, TNBC's with increased expression of GR in immune cells were associated with better survival (Mean survival time 74 vs 41 months, log rank test- p-0.03). TNBC tumors which were GR negative had higher lymph node metastases (p-0.04) and none of the other clinical features like age, menopausal state, tumor size and grade were different between GR positive and negative tumors within TNBC.

Conclusions

Glucocorticoids (GC) are often used to alleviate the adverse symptoms during chemotherapy. Determining the GR status is of importance due to the pro cell survival effect of the glucocorticoids mediated through GR during chemotherapy. Though GC mediated effects on chemotherapy are controversial, our results indicate favourable effects in TNBC.

Investigating the Alteration of Sandstone Pore System and Rock Features by Role of Weighting Materials

Drilled formations are commonly invaded by drilling fluids during the drilling operations, and as a result, the rock pore system will have alterations that consequently alter the rock properties. The objective of this study is to investigate the impact of the most commonly used weighting materials in water-based mud (WBM) on the Berea Buff sandstone pore system and rock characteristics. Rock-mud interaction was imposed by using a customized high-pressure high-temperature filtration test cell under 300 psi differential pressure and 200 °F temperature to simulate downhole conditions during drilling that affect the rock-mud interaction. Extensive lab analysis was accomplished to investigate the rock characteristic alterations in terms of rock porosity, permeability, pore size distribution, flow characteristics, resistivity, and acoustic properties. Ilmenite-WBM showed the maximum values (8.3 cm³ filtrate volume and 7.6 mm cake thickness), while barite recorded the lowest filtrate volume (5.3 cm³) and thickness (3 mm). Nuclear magnetic resonance profiles illustrated the changes in the rock pore system due to the dominant precipitation or dissolution effects. A general porosity reduction was recorded with all mud types that ranged from 4.2 to 9.9% for ilmenite and Micromax, respectively. The rock permeability showed severe damage after mud exposure and a reduction in the pore throat radius. After mud invasion, the rock electrical resistivity showed alterations based on the mineralogical composition of the weighting materials that replaced the saturated brine from the rock pores. Compressional wave velocities (V _p) showed an increasing trend as V _p of Micromax-WBM increased by 4.5%, while hematite- and ilmenite-WBMs recorded the minimum increase of 1.8%. A general reduction was found for shear wave velocities (V _s); Micromax-WBM showed the highest V _s reduction by 6.6%, while ilmenite-WBM recorded the minimum reduction of 1.8%. The pore system alterations are the main reason behind V _p increase, where the rock lithology alterations controlled the V _s changes. The study findings will add more for the rock logging interpretation and rock properties alterations after the mud exposure.

Experimental infection and pathology of two highly pathogenic avian influenza H5N1 viruses isolated from crow and chicken in house crows (Corvus splendens)

We investigated the experimental infection of two highly pathogenic avian influenza H5N1 viruses isolated from crow (A/crow/Assam/142119/2008) and chicken (A/chicken/Sikkim/151466/2009) in house crows (Corvus splendens). Both viruses caused infection in crows, where four out of six and three out of six crows succumbed to H5N1 infection within 11 days post challenge by crow and chicken viruses, respectively. The major clinical signs in crows were wing paralysis, circling and torticollis. The virus shedding detected from swabs was not persistent in both crow nor chicken viruses. Both viruses were isolated more frequently from oral swabs than from cloacal swabs. Both virus strains were isolated from brain, lungs, heart, liver, pancreas, spleen, large intestines of crows that succumbed to H5N1 infection. The surviving birds seroconverted in response to H5N1 virus infection. Microscopically, both viruses caused coagulative necrosis in pancreas and kidneys. Brain showed gliosis and neuronal degeneration. This experimental study highlights that crows could be infected with H5N1 viruses from different hosts with minor differences in pathogenicity. Therefore, it is imperative to carry out surveillance of highly pathogenic avian influenza H5N1 virus in synanthropic birds along with biosecurity measures to mitigate the H5N1 spread in poultry population. Keywords: chicken virus; crow virus; highly pathogenic avian influenza; house crows.

A comparative study evaluating the role of adductor canal block catheter versus intraarticular analgesic infusion on knee pain and range of motion in the immediate postoperative period: a prospective multicenter trial

Postoperative pain after total knee arthroplasty (TKA) is an important determinant of hospital stay and rehabilitation and thereby functional outcome. Adductor canal block (ACB) and intraarticular analgesic infiltration through catheters (IAC) are techniques of multimodal analgesia which have shown to control postoperative pain satisfactorily. The aim of this study is to evaluate the efficacy of ACB versus IAC in reducing immediate postoperative pain and thereby allow early rehabilitation. A multicenter quasi-experimental study was conducted on 511 patients undergoing unilateral primary TKA from March 2016 to April 2017 who either received ACB with catheter (Group I, n = 350 patients) or IAC (Group II, n = 172 patients) for postoperative pain control. All the patients were assessed for severity of pain by Visual Analogue Scale at 8, 24, 48, 72 h postoperatively and knee range of motion (ROM) on the day of discharge. There was no significant difference in pain scores on postoperative day (POD) 0 (1.09 ± 0.30 vs. 0.98 ± 0.46, p = 0.45) and POD 1 (1.21 ± 0.45 vs. 1.00 ± 0.00, p = 0.11) and in mean ROM on the day of discharge between ACB and IAC (88.40° ± 7.96° vs. 88.34° ± 5.74°; p = 0.93) groups. This study shows that both ACB and IAC provide satisfactory postoperative analgesia with sparing of quadriceps function and good knee ROM leading to early rehabilitation and reduced hospital with no advantage of one technique over another.

Voice Rehabilitation After Laryngectomy: A Regional Cancer Centre Experience and Review of Literature

Alaryngeal speech in laryngectomees has revolutionized the patient outlook toward the morbid procedure and the concept of permanent stoma unlike olden era when stigma of stoma with loss of voice was rampant. To analyse acceptance of voice rehabilitation options and their success and management of complications in a tertiary care centre. All patients who underwent laryngectomy from August 2014 to 2018 June at our institution were included in the study. The voice rehabilitation options like oesophageal speech, tracheao-oesophageal puncture and voice prosthesis insertion (TEP), and electrolarynx were explained to the patients. The options put forward to the patients, the importance of Taub test, Interval between treatment and secondary TEP insertion, life span of the prosthesis, Patients acceptance and success rates and the troubleshooting were noted. A total of 96 patients underwent total laryngectomy, 72 patients were willing for rehabilitation. 15% (11) patients had primary TEP, 22% (16) had secondary TEP insertion, esophageal speech in 36% (26) patients and 27% (19) patients opted for the electrolarynx. The rest 24 patients were not keen on any further interventions after laryngectomy. Speech rehabilitation is an integral part in surgical management of carcinoma of the larynx. Alaryngeal speech in laryngectomees have revolutionized the patient outlook towards the morbid procedure. Esophageal speech is the least successful method of rehabilitation but still the cheapest method and requires a lot of motivation. Primary and Secondary TEP insertions have similar success rates. Successful treatment for cancer of larynx ends with successful voice rehabilitation.