39 results on '"Duke MC"'
Search Results
2. Novel composite membranes for gas separation
- Author
-
National Environment Conference (2003 : Brisbane, Qld.), Duke, MC, Hogarth, WHJ, Lu, GQ, Diniz da Costa, JC, Petch, M, and Gray, P
- Published
- 2003
3. Charge tunable thin-film composite membranes by gamma-ray triggered surface polymerization
- Author
-
Reis, R, Duke, MC, Tardy, BL, Oldfield, D, Dagastine, RR, Orbell, JD, Dumee, LF, Reis, R, Duke, MC, Tardy, BL, Oldfield, D, Dagastine, RR, Orbell, JD, and Dumee, LF
- Abstract
Thin-film composite poly(amide) (PA) membranes have greatly diversified water supplies and food products. However, users would benefit from a control of the electrostatic interactions between the liquid and the net surface charge interface in order to benefit wider application. The ionic selectivity of the 100 nm PA semi-permeable layer is significantly affected by the pH of the solution. In this work, for the first time, a convenient route is presented to configure the surface charge of PA membranes by gamma ray induced surface grafting. This rapid and up-scalable method offers a versatile route for surface grafting by adjusting the irradiation total dose and the monomer concentration. Specifically, thin coatings obtained at low irradiation doses between 1 and 10 kGy and at low monomer concentration of 1 v/v% in methanol/water (1:1) solutions, dramatically altered the net surface charge of the pristine membranes from -25 mV to +45 mV, whilst the isoelectric point of the materials shifted from pH 3 to pH 7. This modification resulted in an improved water flux by over 55%, from 45.9 to up 70 L.m-2.h-1, whilst NaCl rejection was found to drop by only 1% compared to pristine membranes.
- Published
- 2017
4. Towards Enhanced Performance Thin-film Composite Membranes via Surface Plasma Modification
- Author
-
Reis, R, Dumee, LF, Tardy, BL, Dagastine, R, Orbell, JD, Schutz, JA, Duke, MC, Reis, R, Dumee, LF, Tardy, BL, Dagastine, R, Orbell, JD, Schutz, JA, and Duke, MC
- Abstract
Advancing the design of thin-film composite membrane surfaces is one of the most promising pathways to deal with treating varying water qualities and increase their long-term stability and permeability. Although plasma technologies have been explored for surface modification of bulk micro and ultrafiltration membrane materials, the modification of thin film composite membranes is yet to be systematically investigated. Here, the performance of commercial thin-film composite desalination membranes has been significantly enhanced by rapid and facile, low pressure, argon plasma activation. Pressure driven water desalination tests showed that at low power density, flux was improved by 22% without compromising salt rejection. Various plasma durations and excitation powers have been systematically evaluated to assess the impact of plasma glow reactions on the physico-chemical properties of these materials associated with permeability. With increasing power density, plasma treatment enhanced the hydrophilicity of the surfaces, where water contact angles decreasing by 70% were strongly correlated with increased negative charge and smooth uniform surface morphology. These results highlight a versatile chemical modification technique for post-treatment of commercial membrane products that provides uniform morphology and chemically altered surface properties.
- Published
- 2016
5. Collaborative Implementation of Robotic Surgery Into an Academic Pediatric Surgery Practice.
- Author
-
Wallace MW, Ram C, Mina A, Lovvorn HN 3rd, Patel A, Hopkins MB, Idrees K, Duke MC, McChesney SL, Khan A, Thomas JC, Jackson GP, Upperman J, and Zamora IJ
- Subjects
- Humans, Child, Adolescent, Male, Female, Cholecystectomy methods, Robotic Surgical Procedures methods, Robotic Surgical Procedures education, Cholecystectomy, Laparoscopic methods, Pediatrics organization & administration, Pediatrics methods
- Abstract
Introduction: Robotic surgery continues to drive evolution in minimally invasive surgery. Due to the confined operative fields encountered, pediatric surgeons may uniquely benefit from the precise control offered by robotic technologies compared to open and laparoscopic techniques. We describe a unique collaborative implementation of robotic surgery into an academic pediatric surgery practice through adult robotic surgeon partnership. We compare robotic cholecystectomy (RC) and laparoscopic cholecystectomy (LC) outcomes, hypothesizing that RC will be equivalent to LC in key quality outcomes., Methods: We evaluate 14 mo of systems development and training, and 24 mo of collaborative operative experience evoking a purposeful tiered case progression, establishing core robotic competencies, prior to advancing operative complexity. Univariate analyses compared LC versus RC., Results: 36 robotic operations were performed in children aged 8-18 y, in a tiered progression from 24 cholecystectomies to 2 ileocecectomies, 2 paraesophageal hernia repairs, 1 anterior rectopexy, 1 spleen-preserving distal pancreatectomy, 1 Heller myotomy, 1 choledochal cyst resection with roux-en-y hepaticojejunostomy, 1 median arcuate ligament release, and 1 thoracic esophageal duplication cyst resection. For LC and RC, there were no significant differences in procedure duration, discharge opioids, hospital readmission, or rates of surgical site infection or bile duct injury., Conclusions: Robotic surgery has potential to significantly enhance pediatric surgery. RC appears equivalent to LC but presents multiple additional theoretical benefits in pediatric patients. Our pilot program experience supports the feasibility and safety of pediatric robotic surgery. We emphasize the importance of a stepwise progression in operative difficulty and collaboration with adult robotic surgery experts., (Copyright © 2024. Published by Elsevier Inc.)
- Published
- 2024
- Full Text
- View/download PDF
6. Portomesenteric Vein Thrombosis After Laparoscopic Sleeve Gastrectomy: A Single-Institution Report.
- Author
-
Wilkinson L, Aubry ST, Haskins IN, Duke MC, Moll S, Dixon R, and Farrell TM
- Subjects
- Humans, Female, Anticoagulants therapeutic use, Risk Factors, Gastrectomy adverse effects, Gastrectomy methods, Retrospective Studies, Postoperative Complications surgery, Laparoscopy adverse effects, Laparoscopy methods, Venous Thrombosis drug therapy, Venous Thrombosis etiology, Obesity, Morbid surgery, Obesity, Morbid complications
- Abstract
Laparoscopic sleeve gastrectomy (LSG) is an effective weight-loss operation. Portomesenteric vein thrombosis (PMVT) is an important complication of LSG. We identified four cases of PMVT after LSG at our institution in women aged 36-47 with BMIs ranging from 44-48 kg/m
2 . All presented 8-19 days postoperatively. Common symptoms were nausea, vomiting, and abdominal pain. Thrombotic risk factors were previous deep vein thrombosis and oral contraceptive use. Management included therapeutic anti-coagulation, directed thrombolysis, and surgery. Complications were readmission, bowel resection, and bleeding. Discharge recommendations ranged from 3-6 months of anticoagulation using various anticoagulants. No consensus was reached on post-treatment hypercoagulable work up or imaging. All cases required multi-disciplinary approach with Surgery, Interventional Radiology, and Hematology. As PMVT is a rare but potentially morbid complication of LSG, further development of tools that quantify preoperative thrombotic risk and clear guidance regarding use of anticoagulants are needed for prevention and treatment of PMVT following LSG., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.- Published
- 2023
- Full Text
- View/download PDF
7. Outcomes of light and midweight synthetic mesh use in clean-contaminated and contaminated ventral incisional hernia repair: an ACHQC comparative analysis.
- Author
-
Polcz ME, Pierce RA, Olson MA, Blankush J, Duke MC, Broucek J, and Bradley JF 3rd
- Subjects
- Adult, Humans, Treatment Outcome, Retrospective Studies, Surgical Mesh adverse effects, Neoplasm Recurrence, Local surgery, Surgical Wound Infection epidemiology, Surgical Wound Infection etiology, Surgical Wound Infection surgery, Herniorrhaphy adverse effects, Recurrence, Incisional Hernia etiology, Incisional Hernia surgery, Hernia, Ventral surgery
- Abstract
Background: Use of macroporous synthetic mesh in contaminated ventral hernia repair has become more frequent. The objective of this study is to compare the outcomes of ventral incisional hernia repair with permanent synthetic mesh in contaminated fields to those in a clean field., Methods: The Abdominal Core Health Quality Collaborative registry, a prospectively updated longitudinal hernia-specific national database, was retrospectively queried for adults who underwent open ventral incisional hernia repair using light or medium-weight synthetic mesh and classified as clean (CDC Class I) or contaminated (CDC Class II/III). Univariate analysis was used to compare demographic information, hernia characteristics, and operative details. Odds ratios (OR) were calculated using multivariable logistic regression for the primary outcome of 30-day surgical site infection (SSI) and secondary outcomes of 30-day surgical site occurrence (SSO), SSO requiring procedural intervention (SSO-PI), and clinical recurrence at one year., Results: 7219 cases met criteria for inclusion; 13.2% of these were contaminated. 83.4% of patients had follow-up data at 30 days and 20.8% at 1 year. The adjusted OR for 30-day SSI in contaminated fields compared to clean was 2.603 (95% CI 1.959-3.459). OR for 30-day SSO was 1.275 (95% CI 1.017-1.600) and 2.355 (95%CI 1.817-3.053) for 30-day SSO-PI. OR for recurrence at one year was 1.489 (95%CI 0.892-2.487). Contaminated cases had higher rates of mesh infection (3.9% vs 0.8%, p < 0.001) and mesh removal (7.3 vs 2.5%, p < 0.001) at 1 year., Conclusions: After adjusting for baseline differences, patients undergoing ventral incisional hernia repair using light or midweight synthetic mesh in contaminated fields have higher odds of 30-day SSI, SSO, and SSO-PI than those performed in clean wounds. The odds of recurrence did not statistically differ and further studies with long-term outcomes are needed to better evaluate the best treatment options for this patient population., (© 2022. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)
- Published
- 2023
- Full Text
- View/download PDF
8. Benefits of Adjuvant Medical Weight Loss Intervention in Setting of Weight Regain and Inadequate Weight Loss After Weight Loss Surgery.
- Author
-
Abel SA, English WJ, Duke MC, Williams DB, Aher CV, Broucek JR, and Spann MD
- Subjects
- Humans, Female, Male, Retrospective Studies, Treatment Outcome, Reoperation, Weight Loss, Gastrectomy methods, Weight Gain, Obesity, Morbid surgery, Laparoscopy methods, Bariatric Surgery, Gastric Bypass methods
- Abstract
Background: Currently, there is no nationally accepted protocol for addressing weight regain or inadequate weight loss after MBS., Objectives: To devise, implement, and evaluate a protocol targeting weight regain or inadequate weight loss in MBS patients at our institution., Setting: Vanderbilt University Medical Center, Nashville, TN, United States., Methods: Patients at least 6 months following primary sleeve gastrectomy (SG) or Roux-en-Y gastric bypass (RYGB) who achieved or were trending toward <50% excess body weight loss or who regained ≥10% of their lowest postoperative weight, were identified and referred for medical weight loss (MWL) intervention. Exclusion criteria were body mass index (BMI) ≤ 27 kg/m
2 , treatment with adjustable gastric banding, and conversion from SG to RYGB., Results: 2274 patients who were >6 months out from surgery were evaluated over 12 months. 93 patients (86% female) met criteria for inclusion. 69 (74%) patients agreed to intervention and were followed for an average of 165 days (SD 106.89 days), demonstrating a mean weight change of -5.11 kg (SD 6.86 kg), and BMI change of -1.81 kg/m2 (SD 2.37 kg/m2 ). Patients who spent <90 days in a MWL program demonstrated less average weight loss (1.75 kg vs 6.48 kg) ( P = .0042), and less change in BMI (-.63 kg/m2 vs -2.29 kg/m2 ) ( P = .0037) when compared to patients who spent >90 days in the MWL intervention., Conclusions: This study identifies criteria for intervention in patients suffering weight regain or inadequate weight loss after MBS and demonstrates that standardized identification and referral for treatment results in modest weight loss.- Published
- 2023
- Full Text
- View/download PDF
9. Preoperative Depression Status and 5 Year Metabolic and Bariatric Surgery Outcomes in the PCORnet Bariatric Study Cohort.
- Author
-
Coughlin JW, Nauman E, Wellman R, Coley RY, McTigue KM, Coleman KJ, Jones DB, Lewis KH, Tobin JN, Wee CC, Fitzpatrick SL, Desai JR, Murali S, Morrow EH, Rogers AM, Wood GC, Schlundt DG, Apovian CM, Duke MC, McClay JC, Soans R, Nemr R, Williams N, Courcoulas A, Holmes JH, Anau J, Toh S, Sturtevant JL, Horgan CE, Cook AJ, and Arterburn DE
- Subjects
- Humans, Depression epidemiology, Gastrectomy, Weight Loss, Retrospective Studies, Treatment Outcome, Obesity, Morbid complications, Obesity, Morbid surgery, Gastric Bypass, Bariatric Surgery
- Abstract
Objective: To examine whether depression status before metabolic and bariatric surgery (MBS) influenced 5-year weight loss, diabetes, and safety/utilization outcomes in the PCORnet Bariatric Study., Summary of Background Data: Research on the impact of depression on MBS outcomes is inconsistent with few large, long-term studies., Methods: Data were extracted from 23 health systems on 36,871 patients who underwent sleeve gastrectomy (SG; n=16,158) or gastric bypass (RYGB; n=20,713) from 2005-2015. Patients with and without a depression diagnosis in the year before MBS were evaluated for % total weight loss (%TWL), diabetes outcomes, and postsurgical safety/utilization (reoperations, revisions, endoscopy, hospitalizations, mortality) at 1, 3, and 5 years after MBS., Results: 27.1% of SG and 33.0% of RYGB patients had preoperative depression, and they had more medical and psychiatric comorbidities than those without depression. At 5 years of follow-up, those with depression, versus those without depression, had slightly less %TWL after RYGB, but not after SG (between group difference = 0.42%TWL, P = 0.04). However, patients with depression had slightly larger HbA1c improvements after RYGB but not after SG (between group difference = - 0.19, P = 0.04). Baseline depression did not moderate diabetes remission or relapse, reoperations, revision, or mortality across operations; however, baseline depression did moderate the risk of endoscopy and repeat hospitalization across RYGB versus SG., Conclusions: Patients with depression undergoing RYGB and SG had similar weight loss, diabetes, and safety/utilization outcomes to those without depression. The effects of depression were clinically small compared to the choice of operation., Competing Interests: The other authors report no conflicts of interest., (Copyright © 2022 The Author(s). Published by Wolters Kluwer Health, Inc.)
- Published
- 2023
- Full Text
- View/download PDF
10. Gastric Bypass Versus Sleeve Gastrectomy: Comparison of Patient Outcomes, Satisfaction, and Quality of Life in a Single-Center Experience.
- Author
-
Varvoglis DN, Lipman JN, Li L, Sanchez-Casalongue M, Zhou R, Duke MC, and Farrell TM
- Subjects
- Humans, Quality of Life, Patient Satisfaction, Gastrectomy adverse effects, Weight Loss, Personal Satisfaction, Treatment Outcome, Gastric Bypass adverse effects, Obesity, Morbid surgery, Obesity, Morbid complications, Laparoscopy adverse effects, Gastroesophageal Reflux etiology, Gastroesophageal Reflux surgery
- Abstract
Background: Laparoscopic sleeve gastrectomy (LSG) is the most common primary bariatric operation performed in the United States. Its relative technical ease, combined with a decreased risk for anatomic and malabsorptive complications make LSG an attractive option compared to laparoscopic gastric bypass (LGB) for many patients and surgeons. However, emerging evidence for progressive gastroesophageal reflux disease (GERD) after LSG, and the inferior weight loss in many studies, suggests that the enthusiasm for LSG requires reassessment. We hypothesized that patient satisfaction and quality of life (QoL) may be lower after LSG compared to LGB because of these differences. Methods: We distributed a survey querying weight-loss outcomes, complications, foregut symptoms, QoL, and overall satisfaction to patients who underwent bariatric operations at our institution between 2000 and 2020 and who had electronic mail contact information available. Mean follow-up was 2.75 ± 2.41 years for LGB patients and 3.37 ± 2.18 ( P = .021) years for LSG patients. We compared these groups for weight-loss outcomes, changes in foregut symptoms, gastrointestinal QoL, postbariatric QoL, and overall satisfaction using appropriate statistical tests. Results: Among 323 respondents, 126 underwent LGB and 197 underwent LSG. LGB patients had larger body mass index (BMI) reduction than LSG patients (-17.16 ± 9.07 kg/m
2 versus -14.87 ± 7.4 kg/m2 , P = .023). LGB patients reported less reflux ( P = .003), with decreased heartburn ( P < .0001) and regurgitation ( P = .0027). However, a greater proportion of LGB patients reported at least one complication ( P = .025). Despite this, more LGB patients reported satisfaction (92.86%) than LSG patients (73.6%). Conclusion: LGB patients are significantly more likely to be satisfied than LSG patients. Factors contributing to the higher level of satisfaction include less GERD and better BMI decrease.- Published
- 2023
- Full Text
- View/download PDF
11. Comparative Safety and Effectiveness of Roux-en-Y Gastric Bypass and Sleeve Gastrectomy for Weight Loss and Type 2 Diabetes Across Race and Ethnicity in the PCORnet Bariatric Study Cohort.
- Author
-
Coleman KJ, Wellman R, Fitzpatrick SL, Conroy MB, Hlavin C, Lewis KH, Coley RY, McTigue KM, Tobin JN, McBride CL, Desai JR, Clark JM, Toh S, Sturtevant JL, Horgan CE, Duke MC, Williams N, Anau J, Horberg MA, Michalsky MP, Cook AJ, Arterburn DE, and Apovian CM
- Subjects
- Adolescent, Adult, Cohort Studies, Ethnic and Racial Minorities, Ethnicity, Female, Gastrectomy adverse effects, Glycated Hemoglobin, Humans, Middle Aged, Recurrence, Retrospective Studies, Treatment Outcome, Weight Loss, Bariatric Surgery adverse effects, Diabetes Mellitus, Type 2 surgery, Gastric Bypass adverse effects, Obesity, Morbid surgery
- Abstract
Importance: Bariatric surgery is the most effective treatment for severe obesity; yet it is unclear whether the long-term safety and comparative effectiveness of these operations differ across racial and ethnic groups., Objective: To compare outcomes of Roux-en-Y gastric bypass (RYGB) and sleeve gastrectomy (SG) across racial and ethnic groups in the National Patient-Centered Clinical Research Network (PCORnet) Bariatric Study., Design, Setting, and Participants: This was a retrospective, observational, comparative effectiveness cohort study that comprised 25 health care systems in the PCORnet Bariatric Study. Patients were adults and adolescents aged 12 to 79 years who underwent a primary (first nonrevisional) RYGB or SG operation between January 1, 2005, and September 30, 2015, at participating health systems. Patient race and ethnicity included Black, Hispanic, White, other, and unrecorded. Data were analyzed from July 1, 2021, to January 17, 2022., Exposure: RYGB or SG., Outcomes: Percentage total weight loss (%TWL); type 2 diabetes remission, relapse, and change in hemoglobin A1c (HbA1c) level; and postsurgical safety and utilization outcomes (operations, interventions, revisions/conversions, endoscopy, hospitalizations, mortality, 30-day major adverse events) at 1, 3, and 5 years after surgery., Results: A total of 36 871 patients (mean [SE] age, 45.0 [11.7] years; 29 746 female patients [81%]) were included in the weight analysis. Patients identified with the following race and ethnic categories: 6891 Black (19%), 8756 Hispanic (24%), 19 645 White (53%), 826 other (2%), and 783 unrecorded (2%). Weight loss and mean reductions in HbA1c level were larger for RYGB than SG in all years for Black, Hispanic, and White patients (difference in 5-year weight loss: Black, -7.6%; 95% CI, -8.0 to -7.1; P < .001; Hispanic, -6.2%; 95% CI, -6.6 to -5.9; P < .001; White, -5.9%; 95% CI, -6.3 to -5.7; P < .001; difference in change in year 5 HbA1c level: Black, -0.29; 95% CI, -0.51 to -0.08; P = .009; Hispanic, -0.45; 95% CI, -0.61 to -0.29; P < .001; and White, -0.25; 95% CI, -0.40 to -0.11; P = .001.) The magnitude of these differences was small among racial and ethnic groups (1%-3% of %TWL). Black and Hispanic patients had higher risk of hospitalization when they had RYGB compared with SG (hazard ratio [HR], 1.45; 95% CI, 1.17-1.79; P = .001 and 1.48; 95% CI, 1.22-1.79; P < .001, respectively). Hispanic patients had greater risk of all-cause mortality (HR, 2.41; 95% CI, 1.24-4.70; P = .01) and higher odds of a 30-day major adverse event (odds ratio, 1.92; 95% CI, 1.38-2.68; P < .001) for RYGB compared with SG. There was no interaction between race and ethnicity and operation type for diabetes remission and relapse., Conclusions and Relevance: Variability of the comparative effectiveness of operations for %TWL and HbA1c level across race and ethnicity was clinically small; however, differences in safety and utilization outcomes were clinically and statistically significant for Black and Hispanic patients who had RYGB compared with SG. These findings can inform shared decision-making regarding bariatric operation choice for different racial and ethnic groups of patients.
- Published
- 2022
- Full Text
- View/download PDF
12. Evaluation of Treatment Differences Between Men and Women Undergoing Ventral Hernia Repair: An Analysis of the Abdominal Core Health Quality Collaborative.
- Author
-
Polcz ME, Olson MA, Bradley J, Broucek J, Duke MC, Prabhu A, Rosen S, Sedrakyan A, Poulose BK, and Pierce RA
- Subjects
- Abdominal Core, Female, Humans, Male, Retrospective Studies, Surgical Mesh, Hernia, Ventral surgery, Incisional Hernia surgery
- Abstract
Background: Sex is emerging as an important clinical variable associated with surgical outcomes and decision making. However, its relevance in regard to baseline and treatment differences in primary and incisional ventral hernia repair remains unclear., Study Design: This is a retrospective cohort study using the Abdominal Core Health Quality Collaborative database to identify elective umbilical, epigastric, or incisional hernia repairs. Propensity matching was performed to investigate confounder-adjusted treatment differences between men and women. Treatments of interest included surgical approach (minimally invasive or open), mesh use, mesh type, mesh position, anesthesia type, myofascial release, fascial closure, and fixation use., Results: A total of 8,489 umbilical, 1,801 epigastric, and 16,626 incisional hernia repairs were identified. Women undergoing primary ventral hernia repair were younger (umbilical 46.4 vs 54 years, epigastric 48.7 vs 52.7 years), with lower BMI (umbilical 30.4 vs 31.5, epigastric 29.2 vs 31.1), and less likely diabetic (umbilical 9.9% vs 11.4%, epigastric 6.8% vs 8.8%). Women undergoing incisional hernia repair were also younger (mean 57.5 vs 59.1 years), but with higher BMI (33.1 vs 31.5), and more likely diabetic (21.4% vs 19.1%). Propensity-matched analysis included 3,644 umbilical, 1,232 epigastric, and 12,480 incisional hernias. Women with incisional hernia were less likely to undergo an open repair (60.2% vs 63.4%, p < 0.001) and have mesh used (93.8% vs 94.8%, p = 0.02). In umbilical and incisional hernia repairs, women had higher rates of intraperitoneal mesh placement and men had higher rates of preperitoneal and retro-muscular mesh placement., Conclusions: Small but statistically significant treatment differences in operative approach, mesh use, and mesh position exist between men and women undergoing ventral hernia repair. It remains unknown whether these treatment differences result in differing clinical outcomes., (Copyright © 2022 by the American College of Surgeons. Published by Wolters Kluwer Health, Inc. All rights reserved.)
- Published
- 2022
- Full Text
- View/download PDF
13. Minimally invasive Heller myotomy with partial posterior fundoplication for the treatment of achalasia: long-term results from a tertiary referral center.
- Author
-
Haskins IN, Strassle PD, Parker BN, Catterall LC, Duke MC, and Farrell TM
- Subjects
- Adult, Fundoplication methods, Humans, Prospective Studies, Quality of Life, Tertiary Care Centers, Treatment Outcome, Esophageal Achalasia surgery, Heller Myotomy methods, Laparoscopy methods
- Abstract
Introduction: Few studies have reported the long-term results of minimally invasive Heller myotomy (HM) for the treatment of achalasia. Herein, we detail our 17-year experience with HM for the treatment of achalasia from a tertiary referral center., Methods: All patients undergoing elective HM at our institution from 2000 to 2017 were identified within a prospective institutional database. These patients were sent mail and electronic surveys to capture their symptoms of dysphagia, chest pain, and regurgitation pre- and postoperatively and were asked to evaluate their postoperative gastrointestinal quality of life. Responses from adult patients who underwent minimally invasive Heller myotomy with partial posterior (i.e., Toupet) fundoplication (HM-TF) were analyzed., Results: 294 patients were eligible for study inclusion; 139 (47%) completed our survey. Median time from HM-TF to survey response was 5.6 years. A majority of patients reported improvement in their dysphagia (91%), chest pain (70%), and regurgitation (87%) symptoms. Patients who underwent HM-TF more than 5 years ago were most likely to report heartburn symptoms. One (1%) patient went on to require esophagectomy for ongoing dysphagia and one (1%) patient required revisional fundoplication for their heartburn symptoms., Conclusions: Minimally invasive Heller myotomy and posterior partial fundoplication is a durable treatment for achalasia over the long term. Additional prospective and multi-institutional studies are needed to validate our results., (© 2021. The Author(s), under exclusive licence to Springer Science+Business Media, LLC part of Springer Nature.)
- Published
- 2022
- Full Text
- View/download PDF
14. Highly-Efficient Sulfonated UiO-66(Zr) Optical Fiber for Rapid Detection of Trace Levels of Pb 2 .
- Author
-
Nazari M, Amini A, Eden NT, Duke MC, Cheng C, and Hill MR
- Subjects
- Humans, Lead chemistry, Metal-Organic Frameworks chemistry, Metals, Heavy chemistry, Optical Fibers, Water chemistry, Water Pollutants, Chemical chemistry, Zirconium chemistry, Lead isolation & purification, Metals, Heavy isolation & purification, Organometallic Compounds chemistry, Phthalic Acids chemistry, Water Pollutants, Chemical isolation & purification
- Abstract
Lead detection for biological environments, aqueous resources, and medicinal compounds, rely mainly on either utilizing bulky lab equipment such as ICP-OES or ready-made sensors, which are based on colorimetry with some limitations including selectivity and low interference. Remote, rapid and efficient detection of heavy metals in aqueous solutions at ppm and sub-ppm levels have faced significant challenges that requires novel compounds with such ability. Here, a UiO-66(Zr) metal-organic framework (MOF) functionalized with SO3H group (SO3H-UiO-66(Zr)) is deposited on the end-face of an optical fiber to detect lead cations (Pb2+) in water at 25.2, 43.5 and 64.0 ppm levels. The SO3H-UiO-66(Zr) system provides a Fabry-Perot sensor by which the lead ions are detected rapidly (milliseconds) at 25.2 ppm aqueous solution reflecting in the wavelength shifts in interference spectrum. The proposed removal mechanism is based on the adsorption of [Pb(OH2)6]2+ in water on SO3H-UiO-66(Zr) due to a strong affinity between functionalized MOF and lead. This is the first work that advances a multi-purpose optical fiber-coated functional MOF as an on-site remote chemical sensor for rapid detection of lead cations at extremely low concentrations in an aqueous system.
- Published
- 2021
- Full Text
- View/download PDF
15. Fellowship or Family? A Comparison of Residency Leave Policies With the Family and Medical Leave Act.
- Author
-
Lumpkin ST, Klein MK, Battarbee AN, Strassle PD, Scarlet S, and Duke MC
- Subjects
- Accreditation legislation & jurisprudence, Cross-Sectional Studies, Female, Humans, Internship and Residency legislation & jurisprudence, Legislation, Medical, Male, Parental Leave legislation & jurisprudence, Policy, Specialty Boards legislation & jurisprudence, Time Factors, United States, Work-Life Balance legislation & jurisprudence, Internship and Residency statistics & numerical data, Medicine statistics & numerical data, Parental Leave statistics & numerical data, Work-Life Balance statistics & numerical data
- Abstract
Background: In 1993, the Family and Medical Leave Act (FMLA) mandated 12 weeks of unpaid, job-protected leave. The current impact of taking 12 weeks of leave during residency has not been evaluated., Methods: We examined the 2018 Accreditation Council for Graduate Medical Education (n = 24) specialty leave policies to determine the impact of 6- and 12-week leave on residency training, board eligibility, and fellowship training. We compared our findings with a 2006 study., Results: In 2018, five (21%) specialties had policy language regarding parental leave during residency, and four (16%) had language regarding medical leave. Median leave allowed was 4 weeks (IQR 4-6). Six specialties (25%) decreased the number of weeks allowed for leave from 2006 to 2018. In 2006, a 6-week leave would cause a 1-year delay in board eligibility in six specialties; in 2018, it would not cause delayed board eligibility in any specialty. In 2018, a 12-week (FMLA) leave would extend training by a median of 6 weeks (mean 4.1, range 0-8), would delay board eligibility by 6-12 months in three programs (mean 2.25, range 0-12), and would delay fellowship training by at least 1 year in 17 specialties (71%). The impact of a 12-week leave was similar between medical and surgical specialties., Conclusions: While leave policies have improved since 2006, most specialties allow for 6 weeks of leave, less than half of what is mandated by the FMLA. Moreover, a 12-week, FMLA-mandated leave would cause significant delays in board certification and entry into fellowship for most residency programs., (Copyright © 2019 Elsevier Inc. All rights reserved.)
- Published
- 2019
- Full Text
- View/download PDF
16. Does Lower Level of Education and Health Literacy Affect Successful Outcomes in Bariatric Surgery?
- Author
-
Mahoney ST, Strassle PD, Farrell TM, and Duke MC
- Subjects
- Adult, Comorbidity, Female, Follow-Up Studies, Humans, Male, Middle Aged, Multivariate Analysis, Obesity, Morbid epidemiology, Postoperative Period, Surveys and Questionnaires, Treatment Outcome, Weight Loss, Bariatric Surgery, Educational Status, Health Literacy, Obesity, Morbid surgery
- Abstract
Background: Our previous study demonstrated that lower level of education was associated with increased rates of postoperative hospital visits following bariatric surgery, potentially secondary to decreased understanding of postoperative expectations. Our follow-up study seeks to evaluate whether patients with lower level of education and health literacy have decreased weight loss success and resolution of comorbidities after bariatric surgery. Methods: Bariatric surgery patients presenting between October 2015 and December 2016 were administered a preoperative questionnaire, which reported education level and contained the Rapid Estimate of Adult Literacy in Medicine-Short Form (REALM-SF) health literacy test. The percentage of excess weight loss (EWL) and improvement of hypertension and diabetes mellitus at 6 months were compared across education level (≤12th grade versus >12th grade) and health literacy score (≤8th grade versus high school level) using Fisher's exact and Wilcoxon tests. Results: Seventy-eight patients were followed until their 6-month postoperative appointment (median 7 months, range 4-12 months); 6 scored ≤8th grade for health literacy on the REALM-SF (8%); and 21 had a ≤12th grade level education (27%). Patients with ≤8th grade on REALM-SF health literacy test lost 35% EWL versus 44% EWL by those with high school level health literacy score ( P = .03). There was no significant difference in EWL compared across education level (44% versus 43%, P = .63). There were no significant differences in comorbidity improvement. Conclusions: The few patients in our cohort with a low health literacy level had a significantly lower EWL following bariatric surgery, and no differences were seen across education level. Increased vigilance in patients with low health literacy may be warranted to ensure excellent outcomes.
- Published
- 2019
- Full Text
- View/download PDF
17. Trends in Utilization and Relative Complication Rates of Bariatric Procedures.
- Author
-
Chung AY, Strassle PD, Schlottmann F, Patti MG, Duke MC, and Farrell TM
- Subjects
- Adult, Databases, Factual, Deglutition Disorders etiology, Female, Gastrectomy methods, Gastrectomy statistics & numerical data, Gastric Bypass methods, Gastric Bypass statistics & numerical data, Gastritis etiology, Gastroplasty statistics & numerical data, Heartburn etiology, Humans, Laparoscopy adverse effects, Laparoscopy statistics & numerical data, Male, Middle Aged, Obesity, Morbid surgery, Portal Vein, Postoperative Complications etiology, Venous Thrombosis etiology, Weight Loss, Gastrectomy adverse effects, Gastrectomy trends, Gastric Bypass adverse effects, Gastric Bypass trends, Gastroplasty adverse effects, Gastroplasty trends
- Abstract
Background: Laparoscopic sleeve gastrectomy and laparoscopic adjustable gastric banding have been popular alternatives to laparoscopic Roux-en-Y gastric bypass due to their technical ease and lower complication rates. Comprehensive longitudinal data are necessary to guide selection of the appropriate bariatric procedures for individual patients., Methods: We used the Truven Heath Analytics MarketScan® database between 2000 and 2015 to identify patients undergoing bariatric surgery. Kaplan-Meier and Cox proportional hazard regression analyses were performed to compare complication rates between laparoscopic gastric bypass and laparoscopic sleeve gastrectomy, as well as between laparoscopic gastric bypass and laparoscopic adjustable gastric banding., Results: 256,830 individuals met search criteria. By 2015, laparoscopic sleeve gastrectomy was the most commonly performed bariatric procedure followed by laparoscopic gastric bypass and then laparoscopic adjustable gastric banding. Overall, laparoscopic sleeve gastrectomy and laparoscopic adjustable gastric banding had fewer complications relative to laparoscopic gastric bypass with the exceptions of heartburn, gastritis, and portal vein thrombosis following sleeve gastrectomy and heartburn and dysphagia following adjustable gastric banding., Conclusion: Laparoscopic sleeve gastrectomy is now the most commonly performed bariatric procedure in the USA. It is reassuring that its overall postoperative complication rates are lower relative to laparoscopic gastric bypass.
- Published
- 2019
- Full Text
- View/download PDF
18. Proof of Concept for Light Conducting Membrane Substrate for UV-Activated Photocatalysis as an Alternative to Chemical Cleaning.
- Author
-
Nyamutswa LT, Zhu B, Navaratna D, Collins S, and Duke MC
- Abstract
Adopting an effective strategy to control fouling is a necessary requirement for all membrane processes used in the water/wastewater treatment industry to operate sustainably. The use of ultraviolet (UV) activated photocatalysis has been shown to be effective in mitigating ceramic membrane fouling by natural organic matter. The widely used configuration in which light is directed through the polluted water to the membrane's active layer suffers from inefficiencies brought about by light absorption by the pollutants and light shielding by the cake layer. To address these limitations, directing light through the substrate, instead of through polluted water, was studied. A UV conducting membrane was prepared by dip coating TiO₂ onto a sintered glass substrate. The substrate could successfully conduct UV from a lamp source, unlike a typical alumina substrate. The prepared membrane was applied in the filtration of a humic acid solution as a model compound to study natural organic matter membrane fouling. Directing UV through the substrate showed only a 1 percentage point decline in the effectiveness of the cleaning method over two cleaning events from 72% to 71%, while directing UV over the photocatalytic layer had a 9 percentage point decline from 84% to 75%. Adapting the UV-through-substrate configuration could be more useful in maintaining membrane functionality during humic acid filtration than the current method being used.
- Published
- 2018
- Full Text
- View/download PDF
19. The effectiveness of army field manual interrogation approaches for educing information and building rapport.
- Author
-
Duke MC, Wood JM, Magee J, and Escobar H
- Subjects
- Deception, Decision Making, Female, Humans, Male, Motivation, United States, Young Adult, Communication, Interpersonal Relations
- Abstract
In 2016, the U.S. Congress mandated that federal intelligence interrogators adhere to the methods of the U.S. Army Field Manual FM 2-22.3 (AFM) and that the manual be revised based upon empirically based evaluations of the interrogation methods' effectiveness with interviewees motivated to withhold information. In the present study, 120 participants took part in a testing situation in which half were induced to cheat. All participants were then accused of cheating and interrogated with either (a) a combination of AFM interrogation approaches that focused on the potential benefits of cooperation with the interviewer (cooperation-focused condition), or (b) a combination of AFM approaches that focused on the potential risks of withholding information (withholding-focused condition). Participants who cheated on the test were significantly more likely to admit their wrongdoing and to provide additional relevant information when interrogated with the withholding-focused approaches than when questioned with the cooperation-focused approaches. The "we know all" AFM approach was especially effective for eliciting truthful admission-related details. Participants reported high rapport with the interrogator in both the cooperation-focused and withholding-focused conditions. These findings indicate that the we-know-all approach can be effective for maintaining rapport and eliciting accurate information in brief interrogations. (PsycINFO Database Record (c) 2018 APA, all rights reserved).
- Published
- 2018
- Full Text
- View/download PDF
20. Acute Biliary Disease.
- Author
-
Chung AY and Duke MC
- Subjects
- Acute Disease, Biliary Tract Diseases etiology, Humans, Biliary Tract Diseases diagnosis, Biliary Tract Diseases surgery
- Abstract
Acute biliary disease is a ubiquitous acute surgical complaint. General surgeons managing emergency surgical patients must be knowledgeable and capable of identifying and caring for common presentations. This article discusses the work-up, diagnosis, and management of the varying pathologies that make up biliary disease including cholelithiasis, cholecystitis, biliary dyskinesia, choledocholithiasis, cholangitis, gallstone pancreatitis, and gallstone ileus. Also addressed are more challenging and rare presentations including pregnancy and bariatric anatomy., (Copyright © 2018 Elsevier Inc. All rights reserved.)
- Published
- 2018
- Full Text
- View/download PDF
21. Dual Functional Ultrafiltration Membranes with Enzymatic Digestion and Thermo-Responsivity for Protein Self-Cleaning.
- Author
-
Vanangamudi A, Dumée LF, Duke MC, and Yang X
- Abstract
Controlling surface⁻protein interaction during wastewater treatment is the key motivation for developing functionally modified membranes. A new biocatalytic thermo-responsive poly vinylidene fluoride (PVDF)/nylon-6,6/poly( N -isopropylacrylamide)(PNIPAAm) ultrafiltration membrane was fabricated to achieve dual functionality of protein-digestion and thermo-responsive self-cleaning. The PVDF/nylon-6,6/PNIPAAm composite membranes were constructed by integrating a hydrophobic PVDF cast layer and hydrophilic nylon-6,6/PNIPAAm nanofiber layer on to which trypsin was covalently immobilized. The enzyme immobilization density on the membrane surface decreased with increasing PNIPAAm concentration, due to the decreased number of amine functional sites. An ultrafiltration study was performed using the synthetic model solution containing BSA/NaCl/CaCl
2, where the PNIPAAm containing biocatalytic membranes demonstrated a combined effect of enzymatic and thermo-switchable self-cleaning. The membrane without PNIPAAm revealed superior fouling resistance and self-cleaning with an RPD of 22%, compared to membranes with 2 and 4 wt % PNIPAAm with 26% and 33% RPD , respectively, after an intermediate temperature cleaning at 50 °C, indicating that higher enzyme density offers more efficient self-cleaning than the combined effect of enzyme and PNIPAAm at low concentration. The conformational volume phase transition of PNIPAAm did not affect the stability of immobilized trypsin on membrane surfaces. Such novel surface engineering design offer a promising route to mitigate surface⁻protein contamination in wastewater applications.- Published
- 2018
- Full Text
- View/download PDF
22. Effects of Education and Health Literacy on Postoperative Hospital Visits in Bariatric Surgery.
- Author
-
Mahoney ST, Tawfik-Sexton D, Strassle PD, Farrell TM, and Duke MC
- Subjects
- Adult, Female, Follow-Up Studies, Humans, Male, Middle Aged, Postoperative Period, Prospective Studies, Risk Factors, Bariatric Surgery, Educational Status, Emergency Service, Hospital statistics & numerical data, Health Literacy, Patient Compliance statistics & numerical data, Patient Readmission statistics & numerical data
- Abstract
Background: Hospital readmissions following bariatric surgery are high and it is necessary to identify modifiable risk factors to minimize this postoperative cost. We hypothesize that lower levels of education and health literacy are associated with increased risks of nonadherence, thus leading to increased emergency department (ED) visits and preventable readmissions postoperatively., Methods: Bariatric surgery patients presenting between October 2015 and December 2016 were administered a preoperative questionnaire that measured education level and the Rapid Estimate of Adult Literacy in Medicine-Short Form (REALM-SF) health literacy test. The rates of postoperative ED visits and readmissions were across education levels (≤12th grade versus >12th grade) and health literacy scores (≤8th grade versus high school level). A composite "hospital visit" outcome was also assessed., Results: Ninety-five patients were enrolled; 23 had ≤12th grade level education and 7 scored ≤8th grade on the REALM-SF. Patients with ≤12th grade education were significantly more likely to have a hospital visit after surgery, compared with patients with >12th grade education (incidence rate ratio [IRR] 3.06, P = .008). No significant difference in ED visits, readmission, or hospital visits was seen when stratified by REALM-SF health literacy score., Conclusions: Lower level of education was associated with more than threefold increased risk of postoperative ED visits and readmission in our center's bariatric surgery patients. A patient's education level is a low-cost means to identify patients who are at risk for postoperative hospital visits, and who may benefit from enhanced educational efforts or more intensive postoperative follow-up.
- Published
- 2018
- Full Text
- View/download PDF
23. Wetting phenomena in membrane distillation: Mechanisms, reversal, and prevention.
- Author
-
Rezaei M, Warsinger DM, Lienhard V JH, Duke MC, Matsuura T, and Samhaber WM
- Subjects
- Distillation methods, Models, Theoretical, Water Purification methods, Wettability, Distillation instrumentation, Membranes, Artificial, Water Purification instrumentation
- Abstract
Membrane distillation (MD) is a rapidly emerging water treatment technology; however, membrane pore wetting is a primary barrier to widespread industrial use of MD. The primary causes of membrane wetting are exceedance of liquid entry pressure and membrane fouling. Developments in membrane design and the use of pretreatment have provided significant advancement toward wetting prevention in membrane distillation, but further progress is needed. In this study, a broad review is carried out on wetting incidence in membrane distillation processes. Based on this perspective, the study describes the wetting mechanisms, wetting causes, and wetting detection methods, as well as hydrophobicity measurements of MD membranes. This review discusses current understanding and areas for future investigation on the influence of operating conditions, MD configuration, and membrane non-wettability characteristics on wetting phenomena. Additionally, the review highlights mathematical wetting models and several approaches to wetting control, such as membrane fabrication and modification, as well as techniques for membrane restoration in MD. The literature shows that inorganic scaling and organic fouling are the main causes of membrane wetting. The regeneration of wetting MD membranes is found to be challenging and the obtained results are usually not favorable. Several pretreatment processes are found to inhibit membrane wetting by removing the wetting agents from the feed solution. Various advanced membrane designs are considered to bring membrane surface non-wettability to the states of superhydrophobicity and superomniphobicity; however, these methods commonly demand complex fabrication processes or high-specialized equipment. Recharging air in the feed to maintain protective air layers on the membrane surface has proven to be very effective to prevent wetting, but such techniques are immature and in need of significant research on design, optimization, and pilot-scale studies., (Copyright © 2018 Elsevier Ltd. All rights reserved.)
- Published
- 2018
- Full Text
- View/download PDF
24. Sleeve Gastrectomy: Surgical Tips.
- Author
-
Chung AY, Thompson R, Overby DW, Duke MC, and Farrell TM
- Subjects
- Bariatric Surgery adverse effects, Female, Gastrectomy adverse effects, Humans, Laparoscopy adverse effects, Male, Middle Aged, Patient Selection, Perioperative Care methods, Postoperative Complications epidemiology, Treatment Outcome, Weight Loss, Bariatric Surgery methods, Gastrectomy methods, Laparoscopy methods, Obesity, Morbid surgery
- Abstract
The vertical sleeve gastrectomy is a bariatric procedure that was originally described as the initial step in the biliopancreatic diversion. It demonstrated effectiveness in weight loss as a single procedure, and the laparoscopic vertical sleeve gastrectomy, as a stand-alone procedure, is now the most commonly performed bariatric surgery worldwide. Due to its relative technical ease and long-term data that have established its durability in treating obesity and its related comorbid conditions, the sleeve gastrectomy has grown in popularity among patients and surgeons. While there are variations in the technical aspects of performing a laparoscopic sleeve gastrectomy, key steps must be undertaken to produce safe and effective outcomes. This article reviews the indications for bariatric surgery, patient selection, surgical technique and tips, perioperative care and complications after sleeve gastrectomy.
- Published
- 2018
- Full Text
- View/download PDF
25. Charge tunable thin-film composite membranes by gamma-ray triggered surface polymerization.
- Author
-
Reis R, Duke MC, Tardy BL, Oldfield D, Dagastine RR, Orbell JD, and Dumée LF
- Abstract
Thin-film composite poly(amide) (PA) membranes have greatly diversified water supplies and food products. However, users would benefit from a control of the electrostatic interactions between the liquid and the net surface charge interface in order to benefit wider application. The ionic selectivity of the 100 nm PA semi-permeable layer is significantly affected by the pH of the solution. In this work, for the first time, a convenient route is presented to configure the surface charge of PA membranes by gamma ray induced surface grafting. This rapid and up-scalable method offers a versatile route for surface grafting by adjusting the irradiation total dose and the monomer concentration. Specifically, thin coatings obtained at low irradiation doses between 1 and 10 kGy and at low monomer concentration of 1 v/v% in methanol/water (1:1) solutions, dramatically altered the net surface charge of the pristine membranes from -25 mV to +45 mV, whilst the isoelectric point of the materials shifted from pH 3 to pH 7. This modification resulted in an improved water flux by over 55%, from 45.9 to up 70 L.m
-2 .h-1 , whilst NaCl rejection was found to drop by only 1% compared to pristine membranes.- Published
- 2017
- Full Text
- View/download PDF
26. Nanofiber Composite Membrane with Intrinsic Janus Surface for Reversed-Protein-Fouling Ultrafiltration.
- Author
-
Vanangamudi A, Dumée LF, Duke MC, and Yang X
- Subjects
- Hydrophobic and Hydrophilic Interactions, Membranes, Artificial, Serum Albumin, Bovine, Ultrafiltration, Nanofibers
- Abstract
Janus nanofiber based composite ultrafiltration (UF) membranes were fabricated via a two-step method, i.e., consecutive electrospinning of hydrophilic nylon-6,6/chitosan nanofiber blend and conventional casting of hydrophobic poly(vinylidene difluoride) (PVDF) dope solution. The as-developed PVDF/nylon-6,6/chitosan membranes were investigated for its morphology using Scanning Electron Microscopy (SEM) by which 18 wt % PVDF was chosen as the optimum base polymer concentration due to optimal degree of integration of cast and nanofiber layers. This membrane was benchmarked against the pure PVDF and PVDF/nylon-6,6 membranes in terms of surface properties, permeability, and its ability to reverse protein fouling. The improved hydrophilicity of the PVDF/nylon-6,6/chitosan membrane was revealed from the 72% reduction in the initial water contact angle compared to the pure PVDF benchmark, due to the incorporation of intrinsic hydrophilic hydroxyl and amine functional groups on the membrane surface confirmed by FTIR. The integration of the nanofiber and cast layers has led to altered pore arrangements offering about 93% rejection of bovine serum albumin (BSA) proteins with a permeance of 393 L·m
-2 ·h-1 ·bar-1 in cross-flow filtration experiments; while the PVDF benchmark only had a BSA rejection of 67% and a permeance of 288 L·m-2 ·h-1 ·bar-1 . The PVDF/nylon-6,6/chitosan membrane exhibited high fouling propensity with 2.2 times higher reversible fouling and 78% decrease in the irreversible fouling compared to the PVDF benchmark after 4 h of filtration with BSA foulants.- Published
- 2017
- Full Text
- View/download PDF
27. Incentive Spirometry After Bariatric Surgery: Yes or No?
- Author
-
Wesp JA, Duke MC, and Farrell TM
- Subjects
- Humans, Hypoxia, Postoperative Period, Spirometry, Bariatric Surgery, Motivation
- Published
- 2017
- Full Text
- View/download PDF
28. Single-Incision Laparoscopic Sleeve Gastrectomy: Yes or No?
- Author
-
Wesp JA, Duke MC, and Farrell TM
- Published
- 2017
- Full Text
- View/download PDF
29. Surgery for Gastroesophageal Reflux Disease in the Morbidly Obese Patient.
- Author
-
Duke MC and Farrell TM
- Subjects
- Esophagogastric Junction surgery, Gastroesophageal Reflux complications, Humans, Obesity, Morbid complications, Bariatric Surgery methods, Fundoplication, Gastroesophageal Reflux surgery, Obesity, Morbid surgery
- Abstract
The prevalence of gastroesophageal reflux disease (GERD) has mirrored the increase in obesity, and GERD is now recognized as an obesity-related comorbidity. There is growing evidence that obesity, specifically central obesity, is associated with the complications of chronic reflux, including erosive esophagitis, Barrett's esophagus, and esophageal adenocarcinoma. While fundoplication is effective in creating a competent gastroesophageal junction and controlling reflux in most patients, it is less effective in morbidly obese patients. In these patients a bariatric operation has the ability to correct both the obesity and the abnormal reflux. The Roux-en-Y gastric bypass is the preferred procedure.
- Published
- 2017
- Full Text
- View/download PDF
30. Mixed Matrix Carbon Molecular Sieve and Alumina (CMS-Al2O3) Membranes.
- Author
-
Song Y, Wang DK, Birkett G, Martens W, Duke MC, Smart S, and Diniz da Costa JC
- Abstract
This work shows mixed matrix inorganic membranes prepared by the vacuum-assisted impregnation method, where phenolic resin precursors filled the pore of α-alumina substrates. Upon carbonisation, the phenolic resin decomposed into several fragments derived from the backbone of the resin matrix. The final stages of decomposition (>650 °C) led to a formation of carbon molecular sieve (CMS) structures, reaching the lowest average pore sizes of ~5 Å at carbonisation temperatures of 700 °C. The combination of vacuum-assisted impregnation and carbonisation led to the formation of mixed matrix of CMS and α-alumina particles (CMS-Al2O3) in a single membrane. These membranes were tested for pervaporative desalination and gave very high water fluxes of up to 25 kg m(-2) h(-1) for seawater (NaCl 3.5 wt%) at 75 °C. Salt rejection was also very high varying between 93-99% depending on temperature and feed salt concentration. Interestingly, the water fluxes remained almost constant and were not affected as feed salt concentration increased from 0.3, 1 and 3.5 wt%.
- Published
- 2016
- Full Text
- View/download PDF
31. Towards Enhanced Performance Thin-film Composite Membranes via Surface Plasma Modification.
- Author
-
Reis R, Dumée LF, Tardy BL, Dagastine R, Orbell JD, Schutz JA, and Duke MC
- Abstract
Advancing the design of thin-film composite membrane surfaces is one of the most promising pathways to deal with treating varying water qualities and increase their long-term stability and permeability. Although plasma technologies have been explored for surface modification of bulk micro and ultrafiltration membrane materials, the modification of thin film composite membranes is yet to be systematically investigated. Here, the performance of commercial thin-film composite desalination membranes has been significantly enhanced by rapid and facile, low pressure, argon plasma activation. Pressure driven water desalination tests showed that at low power density, flux was improved by 22% without compromising salt rejection. Various plasma durations and excitation powers have been systematically evaluated to assess the impact of plasma glow reactions on the physico-chemical properties of these materials associated with permeability. With increasing power density, plasma treatment enhanced the hydrophilicity of the surfaces, where water contact angles decreasing by 70% were strongly correlated with increased negative charge and smooth uniform surface morphology. These results highlight a versatile chemical modification technique for post-treatment of commercial membrane products that provides uniform morphology and chemically altered surface properties.
- Published
- 2016
- Full Text
- View/download PDF
32. UiO-66 MOF end-face-coated optical fiber in aqueous contaminant detection.
- Author
-
Nazari M, Forouzandeh MA, Divarathne CM, Sidiroglou F, Martinez MR, Konstas K, Muir BW, Hill AJ, Duke MC, Hill MR, and Collins SF
- Subjects
- Interferometry instrumentation, Optical Fibers, Organometallic Compounds chemistry, Water chemistry, Water Pollutants, Chemical analysis, Zirconium chemistry
- Abstract
Optical quality metal organic framework (MOF) thin films were integrated, for the first time, to the best of our knowledge, with structured optical fiber substrates to develop MOF-fiber sensors. The MOF-fiber structure, UiO-66 (Zr-based MOF is well known for its water stability), is a thin film that acts as an effective analyte collector. This provided a Fabry-Perot sensor in which concentrations of up to 15 mM Rhodamine-B were detected via wavelength shifts in the interference spectrum.
- Published
- 2016
- Full Text
- View/download PDF
33. Amine Enrichment of Thin-Film Composite Membranes via Low Pressure Plasma Polymerization for Antimicrobial Adhesion.
- Author
-
Reis R, Dumée LF, He L, She F, Orbell JD, Winther-Jensen B, and Duke MC
- Subjects
- Adsorption, Anti-Infective Agents chemistry, Apoptosis drug effects, Apoptosis physiology, Bacterial Adhesion, Biofilms drug effects, Biofilms growth & development, Cell Survival drug effects, Cell Survival physiology, Escherichia coli physiology, Materials Testing, Metal Nanoparticles chemistry, Plasma Gases chemistry, Pressure, Silver chemistry, Surface Properties, Amines chemistry, Anti-Infective Agents pharmacology, Escherichia coli drug effects, Membranes, Artificial, Metal Nanoparticles administration & dosage, Silver pharmacology
- Abstract
Thin-film composite membranes, primarily based on poly(amide) (PA) semipermeable materials, are nowadays the dominant technology used in pressure driven water desalination systems. Despite offering superior water permeation and salt selectivity, their surface properties, such as their charge and roughness, cannot be extensively tuned due to the intrinsic fabrication process of the membranes by interfacial polymerization. The alteration of these properties would lead to a better control of the materials surface zeta potential, which is critical to finely tune selectivity and enhance the membrane materials stability when exposed to complex industrial waste streams. Low pressure plasma was employed to introduce amine functionalities onto the PA surface of commercially available thin-film composite (TFC) membranes. Morphological changes after plasma polymerization were analyzed by SEM and AFM, and average surface roughness decreased by 29%. Amine enrichment provided isoelectric point changes from pH 3.7 to 5.2 for 5 to 15 min of plasma polymerization time. Synchrotron FTIR mappings of the amine-modified surface indicated the addition of a discrete 60 nm film to the PA layer. Furthermore, metal affinity was confirmed by the enhanced binding of silver to the modified surface, supported by an increased antimicrobial functionality with demonstrable elimination of E. coli growth. Essential salt rejection was shown minimally compromised for faster polymerization processes. Plasma polymerization is therefore a viable route to producing functional amine enriched thin-film composite PA membrane surfaces.
- Published
- 2015
- Full Text
- View/download PDF
34. Properties of acid whey as a function of pH and temperature.
- Author
-
Chandrapala J, Duke MC, Gray SR, Zisu B, Weeks M, Palmer M, and Vasiljevic T
- Subjects
- Animals, Hydrophobic and Hydrophilic Interactions, Lactic Acid chemistry, Lactose chemistry, Milk Proteins chemistry, Particle Size, Temperature, Cattle, Hot Temperature, Whey chemistry
- Abstract
Compositional differences of acid whey (AW) in comparison with other whey types limit its processability and application of conventional membrane processing. Hence, the present study aimed to identify chemical and physical properties of AW solutions as a function of pH (3 to 10.5) at 4 different temperatures (15, 25, 40, or 90°C) to propose appropriate membrane-processing conditions for efficient use of AW streams. The concentration of minerals, mainly calcium and phosphate, and proteins in centrifuged supernatants was significantly lowered with increase in either pH or temperature. Lactic acid content decreased with pH decline and rose at higher temperatures. Calcium appeared to form complexes with phosphates and lactates mainly, which in turn may have induced molecular attractions with the proteins. An increase in pH led to more soluble protein aggregates with large particle sizes. Surface hydrophobicity of these particles increased significantly with temperature up to 40°C and decreased with further heating to 90°C. Surface charge was clearly pH dependent. High lactic acid concentrations appeared to hinder protein aggregation by hydrophobic interactions and may also indirectly influence protein denaturation. Processing conditions such as pH and temperature need to be optimized to manipulate composition, state, and surface characteristics of components of AW systems to achieve an efficient separation and concentration of lactic acid and lactose., (Copyright © 2015 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.)
- Published
- 2015
- Full Text
- View/download PDF
35. Changes in glucose fermentation pathways by an enriched bacterial culture in response to regulated dissolved H2 concentrations.
- Author
-
Zheng H, Zeng RJ, Duke MC, O'Sullivan CA, and Clarke WP
- Subjects
- Acetates metabolism, Butanols metabolism, Butyrates metabolism, Ethanol metabolism, Fermentation, Models, Statistical, Culture Media chemistry, Glucose metabolism, Hydrogen metabolism, Solid Waste, Thermoanaerobacterium growth & development, Thermoanaerobacterium metabolism
- Abstract
It is well established that metabolic pathways in the fermentation of organic waste are primarily controlled by dissolved H2 concentrations, but there is no reported study that compares observed and predicted shifts in fermentation pathways induced by manipulating the dissolved H2 concentration. A perfusion system is presented that was developed to control dissolved H2 concentrations in the continuous fermentation of glucose by a culture highly enriched towards Thermoanaerobacterium thermosaccharolyticum (86 ± 9% relative abundance) from an originally diverse consortia in the leachate of a laboratory digester fed with municipal solid waste. Media from a 2.5 L CSTR was drawn through sintered steel membrane filters to retain biomass, allowing vigorous sparging in a separate chamber without cellular disruption. Through a combination of sparging and variations in glucose feeding rate from 0.8 to 0.2 g/L/d, a range of steady state fermentations were performed with dissolved H2 concentrations as low as an equivalent equilibrated H2 partial pressure of 3 kPa. Trends in product formation rates were simulated using a H2 regulation partitioning model. The model correctly predicted the direction of products redistribution in response to H2 concentration changes and the acetate and butyrate formation rates when H2 concentrations were less than 6 kPa. However, the model over-estimated acetate, ethanol and butanol productions at the expense of butyrate production at higher H2 concentrations. The H2 yield at the lowest dissolved H2 concentration was 2.67 ± 0.08 mol H2 /mol glucose, over 300% higher than the yield achieved in a CSTR operated without sparging., (© 2014 Wiley Periodicals, Inc.)
- Published
- 2015
- Full Text
- View/download PDF
36. A second look at the validity of widely used Rorschach indices: comment on Mihura, Meyer, Dumitrascu, and Bombel (2013).
- Author
-
Wood JM, Garb HN, Nezworski MT, Lilienfeld SO, and Duke MC
- Subjects
- Humans, Mental Disorders diagnosis, Rorschach Test
- Abstract
We comment on the meta-analysis by Mihura, Meyer, Dumitrascu, and Bombel (2013), which examined the validity of scores in Exner's Comprehensive System (CS) for the Rorschach. First, we agree there is compelling evidence that 4 categories of cognitive scores-the "Rorschach cognitive quartet"-are related to cognitive ability/impairment and thought disorder. We now feel comfortable endorsing the use of these scores in some applied and research settings. Second, we conducted new meta-analyses (k = 44) for the 4 noncognitive Rorschach scores with highest validity in the Mihura et al. findings. Unlike Mihura et al., we included unpublished dissertations (although we did not attempt to exhaustively unearth all unpublished studies), calculated correlations instead of semipartial correlations, and used the Rorschach International Norms for a larger proportion of comparisons. Our validity estimates for the Suicide Constellation and Weighted Sum of Color were similar to or even higher than those of Mihura et al., although we concluded that support for the Suicide Constellation is limited and that Weighted Sum of Color probably does not measure its intended target. Our validity estimates for Sum Shading and the Anatomy and X-ray score were much lower than those of Mihura et al. We conclude that their meta-analysis accurately reflects the published literature, but their exclusion of unpublished studies led to substantial overestimates of validity for some and perhaps many Rorschach scores. Therefore, the evidence is presently insufficient to justify using the CS to measure noncognitive characteristics such as emotionality, negative affect, and bodily preoccupations., (PsycINFO Database Record (c) 2015 APA, all rights reserved.)
- Published
- 2015
- Full Text
- View/download PDF
37. Performance of porous inorganic membranes in non-osmotic desalination.
- Author
-
Duke MC, Mee S, and da Costa JC
- Subjects
- Aluminum Oxide chemistry, Osmosis, Porosity, Pressure, Silicon Dioxide chemistry, Temperature, Time Factors, Volatilization, Water Supply, Membranes, Artificial, Sodium Chloride isolation & purification, Water Purification methods
- Abstract
The supply security of fresh drinking water is decreasing and raising a critical situation for communities worldwide. Inorganic membranes such as alumina and molecular sieve silica have in the past been shown to be highly effective at separating gases and could offer promise as liquid separators due to their high flux and stability. In this work, we develop a range of inorganic membranes with pore size ranging from 0.3 to 500nm and relate this to separation and transport performance. Best separation results were achieved for the silica membrane pressurised to only 7bar, exhibiting a flux of around 1.8kgm(-2)h(-1) and NaCl rejection of 98% with 3.5wt% (seawater-like) feed. Potable water from seawater-like feed was achieved from the membrane in a single stage after regeneration. Conditions such as pressure and temperature were also modified showing performance characteristics and diffusion mechanisms. The non-osmotic set-up for inorganic membranes is therefore a viable technology for desalination.
- Published
- 2007
- Full Text
- View/download PDF
38. Planning for compliance: OSHA's bloodborne pathogen rule.
- Author
-
Bednar B and Duke MC
- Subjects
- Hepatitis B prevention & control, Humans, Renal Dialysis adverse effects, United States, United States Occupational Safety and Health Administration, Viral Hepatitis Vaccines, Communicable Disease Control methods, Renal Dialysis standards
- Abstract
Overall, the bloodborne pathogen rule constitutes a reasonable response to a significant threat to workplace safety. The risks to dialysis workers from HBV and HIV must be minimized or eliminated and the rule is generally consistent with the consensus approach. Unfortunately for dialysis providers, the rule is not exempt from the law of unintended consequences: government regulation will always have impact beyond its object. Promulgation of the final rule will immediately increase the expenses of dialysis providers. Additionally, the enormity of the HBV and HIV problem coupled with the open-ended nature of the rule's key provisions will almost certainly bring additional costs. So long as dialysis reimbursement remains flat, the unintended consequence of the bloodborne pathogen rule may be to quicken the pace of consolidation in the dialysis service market. The added burden of compliance may be too much for small independent facilities. Only large chains may have the resources to comply and survive. To forestall this effect and to provide employees with maximum protection, all dialysis providers should plan now for compliance.
- Published
- 1990
39. Realizing maximum benefits from incident reporting.
- Author
-
Bednar B and Duke MC
- Subjects
- Humans, Malpractice, Quality Assurance, Health Care, Renal Dialysis adverse effects, Risk Management
- Published
- 1990
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.