Spinal Accessory to Suprascapular Nerve Transfer in Traumatic Brachial Plexus Injury: A Comparative Study of Shoulder Recovery Outcomes in the Anterior versus Posterior Approach and Surgeons' Preference.

BACKGROUND: Conventionally, neural transfer of the spinal accessory nerve to the suprascapular nerve for shoulder abduction in traumatic brachial plexus injury is performed via the anterior approach. However, important advantages of the posterior approach have made it an alternative option, such as the proximity of neural coaptation to the muscle to be reinnervated and negating the effects of a second injury to the suprascapular nerve. METHODS: Retrospective data was collected from 30 patients with brachial plexus injury who underwent spinal accessory nerve to suprascapular nerve transfer over 4 years. There were 15 patients in the anterior-approach group (group A) and 15 in the posterior-approach group (group B). Functional outcome at the shoulder was measured as muscle power and active range of motion at 18 months, and data on patients' satisfaction levels and surgeons' perceptions was also collected. RESULTS: No statistical difference was found in the muscle strength achieved in the 2 groups (P = 0.34), but significant recovery was found in the external rotation achieved by group B (P = 0.02). Statistical difference was insignificant in the 2 groups' active range of motion during abduction and external rotation. The satisfaction index of patients was 86.7% in group B as compared to 68% in group A. Surgeons' perspective showed a faster speed of suprascapular nerve exploration in the posterior approach, with better visibility of supraspinatus muscle contraction, and overall surgeons preferred the posterior approach. CONCLUSIONS: External rotation at the shoulder is better via the posterior approach, but no difference in abduction was noted. Patients who underwent the posterior approach were more satisfied with the recovery, and surgeons preferred the posterior approach.

Comparison of Fibrin Glue With Conventional Suturing in Peripheral Nerve Repairs: A Study of Sensory and Motor Outcomes.

BACKGROUND: Nerve injuries have traditionally been repaired with sutures, and this method is considered the gold standard technique in the management of nerve injuries. However, fibrin glue has recently become a promising tool for repairing nerve injuries and has advantages including ease of usability, atraumatic application technique, and decreased co-optation time of the nerves. This study aims to clinically evaluate the efficacy of nerve repair with fibrin glue compared with the usual suture technique in terms of sensory and motor outcomes. METHODS: A total of 80 patients were included in the study; 50 patients underwent primary nerve repair, and 30 patients underwent Oberlin's repair. These subsets were randomly divided into two groups in which the nerves were repaired with microsutures in one group and fibrin glue in the other group. RESULTS: In the comparison of fibrin glue with microsutures, there were no significant differences between the two groups in the 2-point discrimination (2PD) test, Semmes-Weinstein test, motor function, and Disabilities of the Arm, Shoulder, and Hand (DASH) questionnaire scores. However, the co-optation times were significantly shorter with fibrin glue than with microsutures. CONCLUSION: Based on our findings, nerve repair with fibrin glue is as effective as microsutures in terms of sensory and motor recovery and has added advantages of ease of usability and shorter repair times. Therefore, fibrin glue may be an effective alternative to sutures in nerve repair.

Feasibility of Endovascular Deep Brain Stimulation of Anterior Nucleus of the Thalamus for Refractory Epilepsy.

BACKGROUND AND OBJECTIVES: Deep brain stimulation (DBS) has developed into an effective therapy for several disease states including treatment-resistant Parkinson disease and medically intractable essential tremor, as well as segmental, generalized and cervical dystonia, and obsessive-compulsive disorder (OCD). Dystonia and OCD are approved with Humanitarian Device Exemption. In addition, DBS is also approved for the treatment of epilepsy in the anterior nucleus of the thalamus. Although overall considered an effective treatment for Parkinson disease and epilepsy, a number of specific factors determine the treatment success for DBS including careful patient selection, effective postoperative programming of DBS devices and accurate electrode placement. Furthermore, invasiveness of the procedure is a rate limiter for patient adoption. It is desired to explore a less invasive way to deliver DBS therapy. METHODS: Here, we report for the first time the direct comparison of endovascular and parenchymal DBS in a triplicate ovine model using the anterior nucleus of the thalamus as the parenchymal target for refractory epilepsy. RESULTS: Triplicate ovine studies show comparable sensing resolution and stimulation performance of endovascular DBS with parenchymal DBS. CONCLUSION: The results from this feasibility study opens up a new frontier for minimally invasive DBS therapy.

Impacted Ectopic Maxillary Incisor at the Margins of an Oronasal Palatal Fistula.

An oronasal fistula is one of the most common complications that can occur after cleft palate surgeries. Some of the reasons for the failure of repair are the closure of palatal flaps under tension, vascular compromise, and infection. We present a case of a 10-year-old patient who experienced nasal regurgitation during feeding, four years after undergoing a redo palatoplasty. The reason was identified as an impacted maxillary incisor located at the fistula site. The patient was managed with the closure of the oronasal palatal fistula, with a two-layered repair technique using bilateral mucoperiosteal flaps after the removal of the impacted tooth.

Post-Traumatic Radial Artery Pseudoaneurysm at the Wrist Level: A Case Report.

A pseudoaneurysm is a collection of blood outside the arterial lumen but remains in continuity with the lumen and lined by fibrous tissue. Radial artery pseudoaneurysm is a rare entity mostly occurring due to iatrogenic reasons. Traumatic causes are rare. In this case report, we report a post-traumatic left radial artery pseudoaneurysm at the wrist level in a 20-year-old male patient. The patient was treated with end-to-end repair of excised pseudoaneurysm with a vein graft taken from the radial artery vena comitantes through the same incision.

Long-term health consequences of COVID-19 in survivors hospitalised at a tertiary care hospital and their correlation with acute COVID-19 severity and associated risk factors.

OBJECTIVES: To determine post-COVID syndromes in the Indian population, correlating a wide spectrum of post-COVID manifestations with acute disease severity and associated risk factors. BACKGROUND: Post-COVID Syndrome (PCS) is defined as signs and symptoms that develop during or after acute COVID-19 infection. DESIGN OF STUDY: This is a prospective observational cohort with repetitive measurements. METHODS: The study followed RT-PCR confirmed COVID-19-positive survivors discharged from HAHC Hospital, New Delhi, for a period of 12 weeks. The patients were interviewed over the phone at 4 weeks and 12 weeks from the onset of symptoms for evaluation of clinical symptoms and health-related quality of life parameters. RESULTS: A total of 200 patients completed the study. At the baseline, 50% of the patients were categorised as severe based on their acute infection assessment. At 12 weeks after symptom onset, fatigue (23.5%), hair loss (12.5%) and dyspnea (9%) were the main persistent symptoms. The incidence of hair loss (12.5%), memory loss (4.5%) and brain fog (5%) were found to be increased as compared to the acute infection period. Severity of the acute COVID infection behaved as an independent predictor for the development of PCS, with high odds of experiencing persistent cough (OR = 13.1), memory loss (OR = 5.2) and fatigue (OR = 3.3). Further, 30% of subjects in the severe group experienced statistically significant fatigue at 12 weeks (p < .05). CONCLUSION: From the results of our study, it can be concluded that there is a huge disease burden of post-COVID Syndrome (PCS). The PCS comprised multisystem symptoms ranging from serious complaints of dyspnea, memory loss and brain fog to non-serious complaints of fatigue and hair loss. Severity of the acute COVID infection behaved as an independent predictor for the development of PCS. Our findings strongly recommend vaccination against COVID-19, for protection from disease severity as well as prevention of PCS. RELEVANCE TO CLINICAL PRACTICE: The findings of our study support the multidisciplinary approach required for the management of PCS with a team comprising of physicians, nurses, physiotherapists and psychiatrists working in close coordination for the rehabilitation of these patients. As nurses are considered the most trusted professionals in the community and the class of health workers associated with rehabilitation, focus should be given to educating them on PCS, which would prove to be an important strategy for efficient monitoring and long-term management of COVID-19 survivors.

Expression of Angiopoetin-Like Protein-4 and Kidney Injury Molecule-1 as Preliminary Diagnostic Markers for Diabetes-Related Kidney Disease: A Single Center-Based Cross-Sectional Study.

The purpose of the study was to examine the urinary levels of kidney injury molecule-1 (KIM-1) and angiopoietin-like protein-4 (ANGPTL-4) in individuals with diabetic kidney disease (DKD) and their association with established DKD diagnostic markers such as albuminuria and estimated glomerular filtration rate (eGFR). Levels of ANGPTL-4 and KIM-1 were estimated in urine samples. A total of 135 participants were recruited into three groups: 45 diabetes type 2 patients in the control group and 90 DKD patients in two disease groups. Concentrations of ANGPTL-4 and KIM-1 were conclusively related to the urinary albumin-creatinine ratio (UACR). Also, the levels of both ANGPTL-4 and KIM-1 were negatively associated with the eGFR. Multivariable Poisson regression analysis showed that urinary ANGPTL-4 (PR: 3.40; 95% CI: 2.32 to 4.98; p < 0.001) and KIM-1 (PR: 1.25; 95% CI: 1.14 to 1.38; p < 0.001) were prevalent in DKD patients. Receiver operating characteristic (ROC) analysis of urinary ANGPTL-4 and KIM-1 in the combined form resulted in an area under curve (AUC) of 0.967 (95%CI: 0.932-1.000; p < 0.0001) in the microalbuminuria group and 1 (95%CI: 1.000-1.000; p < 0.0001) in the macroalbuminuria group. The association of urinary levels of ANGPTL-4 and KIM-1 with UACR and eGFR and significant prevalence in the diabetic kidney disease population illustrates the diagnostic potential of these biomarkers.

A mixed method study to assess notification of tuberculosis patients by private practitioners in New Delhi, India.

Background: A staggering one million tuberculosis (TB) cases are missing from notification, most of them being diagnosed and treated in the private sector. To curb this issue, the Government of India declared TB as a notifiable disease and NIKSHAY was launched in 2012. However, even after years of implementation, as per the report published by TB India 2020, the proportion of private case notification of total TB cases is very low. Objectives: The objectives of the study were to assess the current practices related to TB Notification being followed by private practitioners of Delhi and to explore the enablers and barriers to TB notification among private-sector treatment providers. Methods: This cross-sectional study was done from January 2019 to January 2020. Six hundred doctors were line listed under the chosen TB unit, 375 gave consent and in depth interview was conducted among them. Data were collected on the reporting status and facilitators and barrier toward NIKSHAY reporting were assessed. For the qualitative component, focused group discussions were done. Results: Out of 375 private practitioners, over two-third (68%) practitioners reported that they were not treating TB patients. Out of 108 doctors treating patients only 50% were reporting the cases. Major reason cited for not reporting was "don't know how to" and major barrier considered was "lack of training." Conclusion: Strategies such as training and retraining, and one-to-one sensitization of private practitioners to address barriers may enhance TB notification.

Assessment of potential risk factors for COVID-19 among health care workers in a health care setting in Delhi, India -a cohort study.

INTRODUCTION: Healthcare workers (HCW) are most vulnerable to contracting COVID-19 infection. Understanding the extent of human-to-human transmission of the COVID-19 infection among HCWs is critical in managing this infection and for policy making. We did this study to estimate new infection by seroconversion among HCWs in recent contact with COVID-19 and predict the risk factors for infection. METHODS: A cohort study was conducted at a tertiary care COVID-19 hospital in New Delhi during the first and second waves of the COVID-19 pandemic. All HCWs working in the hospital during the study period who came in recent contact with the patients were our study population. The data was collected by a detailed face-to-face interview, serological assessment for anti- COVID-19 antibodies at baseline and end line, and daily symptoms. Potential risk factors for seroprevalence and seroconversion were analyzed by logistic regression keeping the significance at p<0.05. RESULTS: A total of 192 HCWs were recruited in this study, out of which 119 (62.0%) were seropositive. Almost all were wearing Personal protective equipment (PPE) and following Infection prevention and control (IPC) measures during their recent contact with a COVID-19 patient. Seroconversion was observed among 36.7% of HCWs, while 64.0% had a serial rise in the titer of antibodies during the follow-up period. Seropositivity was negatively associated with being a doctor (odds ratio [OR] 0.35, 95% Confidence Interval [CI] 0.18-0.71), having COVID-19 symptoms (OR 0.21, 95% CI 0.05-0.82), having comorbidities (OR 0.14, 95% CI 0.03-0.67), and received IPC training (OR 0.25, 95% CI 0.07-0.86), while positively associated with partial (OR 3.30, 95% CI 1.26-8.69), as well as complete vaccination for COVID-19 (OR 2.43, 95% CI 1.12-5.27). Seroconversion was positively associated with doctor as a profession (OR 13.04, 95% CI 3.39-50.25) and with partially (OR 4.35, 95% CI 1.07-17.65), as well as fully vaccinated for COVID-19 (OR 6.08, 95% CI 1.73-21.4). No significant association was observed between adherence to any IPC measures and PPE adopted by the HCW during the recent contact with COVID-19 patients and seroconversion. CONCLUSION: Almost all the HCW practiced IPC measures in these settings. High seropositivity and seroconversion are most likely due to concurrent vaccination against COVID-19 rather than recent exposure to COVID-19 patients. Further studies using anti-N antibodies serology may help us find the reason for the seropositivity and seroconversion among HCWs.

Dosimetric Evaluation of Different Optimization Algorithms Used in Interstitial Brachytherapy of Cervical Carcinoma.

Background: Conventional optimization techniques are based on the planning approach in which positions and weights are varied to generate the desired dose distribution. Inverse planning simulated annealing (IPSA) is an advanced optimization method developed to automatically determine a suitable combination of positions to design an acceptable plan. Objective: In this study, three optimization techniques namely IPSA, graphical optimization (GROPT), and geometrical optimization (GOPT) methods are compared in high-dose-rate interstitial brachytherapy of cervical carcinoma. Material and Methods: In this retrospective study, twenty computed tomography (CT) data sets of 10 cervical cancer patients treated with Martinez Universal Perineal Interstitial Template-based interstitial brachytherapy were studied. The treatment plans generated were optimized using the IPSA, and GOPT methods. The prescribed dose was 24 Gy in 4 fractions. Plans produced using IPSA, GrOPT, and GOPT techniques were analyzed for comparison of dosimetric parameters, including target coverage, homogeneity, conformity, and organs at risk (OAR) doses. Results: V100 values for IPSA, GrOPT and GOPT plans were 95.81±2.33%, 93.12±2.76% and 88.90±4.95%, respectively. The mean D90 values for the IPSA, GrOPT, and GOPT plans were 6.45±0.15 Gy, 6.12±0.21 Gy, and 5.85±0.57 Gy, respectively. Significantly lower doses of OAR were in the IPSA plans that were more homogeneous (HI=0.66). Conformity was comparatively higher in IPSA-based plans (CI=0.75). Conclusion: IPSA plans were superior and resulted in better target coverage, homogeneity, conformity, and minimal OAR doses.

Efficacy of polyherbal formulations for prevention of COVID-19 infection in high-risk subjects: A randomized open-label controlled clinical trial.

COVID-19 is arguably the biggest health crisis the world has faced in the 21st century. Therefore, two of the polyherbal formulations, Infuza and Kulzam were assessed for the prevention of COVID-19 infection as a repurposed medication. Four hundred seven high-risk subjects were recruited in the present open-label randomized controlled clinical trial for eligibility. After assessment for eligibility, remaining 251 subjects were randomized to the test and control groups. Further, 52 high-risk subjects in Infuza, 51 in Kulzam, 51 in Infuza & Kulzam and 53 in control group completed the 14 days of intervention/assessment. The phenotyping of lymphocytes at baseline (0 day) and after 14 days of treatment was carried out by flow cytometry assays. A total of 15.09% high-risk subjects in control group turned positive as compared to only 7.69% in Infuza, 3.92% in Kulzam and 1.96% in Infuza & Kulzam groups. The rate of conversion to COVID-19 infection in Infuza & Kulzam group was minimal and statistically significant as compared to control group (p0.017). No significant changes in phenotype of lymphocytes (T, B, NK cells), absolute lymphocyte count and cytokine levels were found in study groups. However, there was a decreasing trend of hs-CRP level in high-risk subjects after intervention of polyherbal formulations for 14 days. The combination of Infuza and Kulzam may synergistically prevent COVID-19 infection in high-risk subjects of COVID-19.

Assessment of frontline health workers in providing services for malaria elimination in the tribal district of Mandla, Madhya Pradesh.

Background: The Accredited Social Health Activists (ASHAs) and Auxiliary Nurse Midwives (ANMs) are the frontline health staff that provide essential health care services, including diagnosis and treatment of malaria. To support India's malaria-free goal by 2030, a project known as the Malaria Elimination Demonstration Project (MEDP) in the tribal district of Mandla was initiated. This study assessed the capabilities of ASHAs and ANMs of Mandla district to diagnose and treat malaria. Methods: A cross-sectional study was conducted in the 71 sub-centers and their villages where at least one positive malaria case was diagnosed in 2019. Pre-designed and validated tools were used to assess the knowledge, attitude, and practices of ASHAs and ANMs. Analysis was performed using descriptive statistics and multivariate logistic regressions. Results: Malaria is the fifth priority of the ASHAs and ANMs of Mandla district. Good level of knowledge regarding malaria etiology, diagnosis, and prevention was found, but the ability to treat a malaria case as per the national drug policy was below expectations. Frequent and prolonged stockouts of drugs and diagnostics were found. Logistic regressions revealed better capacity of ANMs to dispense correct treatment as compared to the ASHAs. Improvement was seen in the ASHAs ability to interpret rapid diagnostic test (RDT) results following trainings by MEDP Mandla. Conclusion: There is a need to increase the capabilities of the frontline health staff of Mandla for malaria diagnosis and treatment. Continuous trainings and a robust supply chain management system is required to equip the ASHAs and ANMs to effectively deliver malaria diagnosis and treatment services.

Assessment of frailty and outcome of an ethnogeriatric population in periurban slums of Delhi, India - An interventional strategy in a primary health care setting.

INTRODUCTION: The burden of frailty and aging will have a profound impact on the economy along with the deteriorating clinical condition of the olds. AIM: This study aim was to assess frailty of an ethnogeriatric cohort and associate it with domains of quality of life in Delhi along with a follow-up outcome assessment. METHOD: Edmonton frail scale on an ethnogeriatric cohort of 200 individuals in periurban slums of Delhi was used and associated with quality of life, calculated by the WHO-BREF -QOL questionnaire. An interventional strategy for healthy aging was adopted, and a follow-up outcome assessment was done to look out for mortality or morbidity. RESULT: There were 37% frail with a mean score of 60 and 25% prefrails beyond 60 years with a significant increase in frailty with age. Females, single, working, and illiterate elderly were frailer as compared to their counterparts. Social domain followed by psychological domain of the QOL had least scores in the frail elderly. Olds, away from their place of origin were 25 times more likely to be frail and had lesser family integration, assessed by regression analysis. Nearly 6% died, with 21% of hospital readmissions after a 6-month follow-up. DISCUSSION: An earlier start of assessment would give us more time to react and respond and be pro-active for healthy aging besides taking into consideration the diverse ethnography in our country. CONCLUSION: Cross-cultural variations need the physicians to address the health care disparities and language barriers so as to make interventions more convenient.

Multilayer fabrication of durable catheter-deployable soft robotic sensor arrays for efficient left atrial mapping.

Devices that perform cardiac mapping and ablation to treat atrial fibrillation provide an effective means of treatment. Current devices, however, have limitations that either require tedious point-by-point mapping of a cardiac chamber or have limited ability to conform to the complex anatomy of a patient's cardiac chamber. In this work, a detailed, scalable, and manufacturable technique is reported for fabrication of a multielectrode, soft robotic sensor array. These devices exhibit high conformability (~85 to 90%) and are equipped with an array of stretchable electronic sensors for voltage mapping. The form factor of the device is intended to match that of the entire left atrium and has a hydraulically actuated soft robotic structure whose profile facilitates deployment from a 13.5-Fr catheter. We anticipate that the methods described in this paper will serve a new generation of conformable medical devices that leverage the unique characteristics of stretchable electronics and soft robotics.

A comparative study of topical tacrolimus and topical triamcinolone acetonide in nodular scabies.

The aim of this study was to compare the efficacy and safety of 0.1% triamcinolone acetonide and 0.03% tacrolimus ointment for the treatment of nodular lesions of scabies. In this double-blind randomized controlled trial, 50 Indian men with postscabeitic persistent nodular lesions (labelled to have nodular scabies (NS)/postscabies prurigo (PSP)) over the external genitalia, were enrolled. They were randomized into two groups to receive either a mid-potency topical corticosteroid (TCS); triamcinolone acetonide 0.1% ointment twice daily, or topical calcineurin inhibitor (CNI); tacrolimus ointment 0.03% twice daily over the nodular lesions for 2 weeks. All patients were followed up on three visits: 1, 2, and 6 weeks, for assessment. Efficacy was evaluated by 5-point range investigator-assessed VAS, and a 4-point severity of pruritus scale (SPS) score. The mean VAS score was higher in triamcinolone group compared to tacrolimus group at both follow-ups, although statistically significant only at 2nd week visit. The fall in mean SPS at both follow-ups was also higher in the steroid group, but the difference was not statistically significant. While, the overall tolerance to either ointment was excellent, mild hypopigmentation, and epidermal atrophy were detected on dermoscopic evaluation of the treated areas at the 2nd week visit in a small subset of patients in the triamcinolone group. The frequency of relapse of lesions and/or pruritus after four weeks of the 2-week therapy was high in both the groups (higher in tarolimus group). Conclusively, although both treatment options provided safe and satisfactory short term improvement, the results from this study suggest an overall higher efficacy of a mid-potency TCS like triamcinolone 0.1% over topical CNI like tacrolimus 0.03%, in the short-term treatment of nodular lesions of NS/PSP. Topical CNIs may be considered for maintenance of effect, if prolonged therapy is warranted.

A Catheter-Deployable Soft Robotic Inflatable Basket for Enhanced Conformability to the Left Atrium of the Heart.

This paper presents the design, fabrication, and test results for a novel basket catheter that utilizes soft robotic technology, which can conform to complex patient anatomy. Two designs of basket-shaped balloons in three sizes are fabricated based on a CO2 laser cutting method from thin (<50 µm) thermoplastic polyurethane. The balloons are deployed in four soft-material 3D printed left atria, whose geometries are based on volume rendered segmentation of cardiac computed tomography (CT) scans. The coverage and conformability to the realistic patient anatomies is tracked with the small patches of pH paper that indicate, via a color change, contact with a basic solution that lined the 3D printed atriums. The conformability of these inflatable basket catheters is demonstrated as high as (85%) for the optimized design. To visualize the balloon's performance, microCT images of balloons deployed in 3D printed models are shown. These images show the ability of the balloons to adapt to complex patient anatomy and do not exhibit any spline bunching or other deleterious mechanical behavior. This platform has the potential to be coupled with electrical sensors for simultaneous multisensor mapping of atrial fibrillation and other cardiac arrhythmias.

Interlimb coupling in poststroke rehabilitation: a pilot randomized controlled trial.

Background: The interlimb coupling, coordination between the limbs, gets hampered in post-stroke hemiparesis. Most of the poststroke motor regimes primarily focus on the more affected limb.Objectives: To develop an interlimb coupling protocol and assess its feasibility and effect on motor recovery, gait and disability among post-stroke subjects.Design: A pilot randomized controlled, doubled blinded trialSetting: A rehabilitation instituteMethods: 50 post-stroke (> 6 months) hemiparetic subjects (Brunnstrom recovery stage ≥ 3) were randomly divided into experimental (n=26) and control (n=24) groups. The 8-week experimental intervention (3 sessions of 1 hour each, per week) comprised activities demanding coordinated, alternate, and rhythmic use of the affected as well as the less-affected limbs. The outcome measures were feasibility of activities, Fugl-Meyer assessment (FMA), Rivermead visual gait assessment (RVGA), Functional ambulation category (FAC) and modified Rankin scale (mRS).Results: The experimental protocol was found to be feasible by the participants. Post intervention, the experimental group exhibited highly significant difference for FMA (mean difference = 7.12, 95% CI = 5.71 - 8.53, p < 0.001), RVGA reduction (mean difference = - 6.32, 95% CI = 7.51 - 5.13, p < 0.001), and median FAC enhancement (p < 0.001) in comparison to the controls. However, the median mRS level of experimental group did not change significantly (p = 0.056) when compared with the controls.Conclusions: The interlimb coupling training, a feasible program may enhance recovery of the upper and lower limbs and gait in stroke. Further definitive randomized trials are warranted to validate the present findings.

Stress-localized durable anti-biofouling surfaces.

Growing demands for bio-friendly antifouling surfaces have stimulated the development of new and ever-improving material paradigms. Despite notable progress in bio-friendly coatings, the biofouling problem remains a critical challenge. In addition to biofouling characteristics, mechanically stressed surfaces such as ship hulls, piping systems, and heat exchangers require long-term durability in marine environments. Here, we introduce a new generation of anti-biofouling coatings with superior characteristics and high mechanical, chemical and environmental durability. In these surfaces, we have implemented the new physics of stress localization to minimize the adhesion of bio-species on the coatings. This polymeric material contains dispersed organogels in a high shear modulus matrix. Interfacial cavitation induced at the interface of bio-species and organogel particles leads to stress localization and detachment of bio-species from these surfaces with minimal shear stress. In a comprehensive study, the performance of these surfaces is assessed for both soft and hard biofouling including Ulva, bacteria, diatoms, barnacles and mussels, and is compared with that of state-of-the-art surfaces. These surfaces show Ulva accumulation of less than 1%, minimal bacterial biofilm growth, diatom attachment of 2%, barnacle adhesion of 0.02 MPa and mussel adhesion of 7.5 N. These surfaces promise a new physics-based route to address the biofouling problem and avoid adverse effects of biofouling on the environment and relevant technologies.

An in situ method on kinetics of gas hydrates.

Gas hydrate formation is a high-risk and common flow assurance problem in subsea oil production plants. The modern strategies to mitigate hydrate formation have switched from thermodynamic inhibition to risk management. In this new mitigation strategy, hydrate formation is allowed as long as it does not lead to plugging of pipelines. Thus, understanding the growth kinetics of gas hydrates plays a critical role in risk management strategies. Here, we report a new accurate and in situ approach to probe the kinetics of gas hydrate formation. This approach is based on the hot-wire method, which probes the thermal properties of the medium surrounding the hot-wire. As the thermal properties of gas hydrate and its initial constituents are different, variation in these properties is used to probe kinetics of hydrate growth front. Through this in situ method, we determine kinetics of cyclopentane hydrate formation in both mixing and flow conditions. The findings show that at ambient pressure and a temperature of 1-2 °C, the hydrate formation rate under mixing condition varies between 1.9 × 10-5 and 3.9 × 10-5 kg m-2 s-1, while in flow condition, this growth rate drops to 4.5 × 10-6 kg m-2 s-1. To our knowledge, this is the first reported growth rate of cyclopentane hydrate. This in situ approach allows us to probe kinetics of hydrate formation where there is no optical access and provides a tool to rationally design risk management strategies for subsea infrastructures.

Ultrahigh Evaporative Heat Fluxes in Nanoconfined Geometries.

Advancement in high-performance photonics/electronics devices has boosted generated thermal energy, making thermal management a bottleneck for accelerated innovation in these disciplines. Although various methods have been used to tackle the thermal management problem, evaporation with nanometer fluid thickness is one of the most promising approaches for future technological demands. Here, we studied thin-film evaporation in nanochannels under absolute negative pressure in both transient and steady-state conditions. We demonstrated that thin-film evaporation in nanochannels can be a bubble-free process even at temperatures higher than boiling temperature, providing high reliability in thermal management systems. To achieve this bubble-free characteristic, the dimension of nanochannels should be smaller than the critical nucleolus dimension. In transient evaporative conditions, there is a plateau in the velocity of liquid in the nanochannels, which limits the evaporative heat flux. This limit is imposed by liquid viscous dissipation in the moving evaporative meniscus. In contrast, in steady-state condition, unprecedented average interfacial heat flux of 11 ± 2 kW cm-2 is achieved in the nanochannels, which corresponds to liquid velocity of 0.204 m s-1. This ultrahigh heat flux is demonstrated for a long period of time. The vapor outward transport from the interface is both advective and diffusion controlled. The momentum transport of liquid to the interface is the limiting physics of evaporation at steady state. The developed concept and platform provide a rational route to design thermal management technologies for high-performance electronic systems.