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1.
Clin Neurol Neurosurg ; 217: 107260, 2022 Apr 28.
Artigo em Inglês | MEDLINE | ID: mdl-35500420

RESUMO

INTRODUCTION: Obesity adversely affects the outcome in trauma patients. However, the impact of obesity on the severity of traumatic brain injury (TBI) and outcomes is not well known. This study aimed to explore the impact of obesity/body mass index on the severity and outcomes following TBI. METHODS: A systematic review of the literature was conducted using PRISMA guidelines to answer three questions: Q1: Is obesity/increased BMI associated with less risk of head injury? Q2: Whether obesity is associated with less severity of head injury? Q3: What is the impact of obesity/BMI on outcomes following head injury? A comprehensive search using keywords and MeSH terms was conducted in PUBMED, Cochrane database, Google Scholar, SCOPUS, WEB of Science Core Collection, and ScIELO index (Last day of search 06.06.2021). We used the Newcastle-Ottawa assessment scale (NOS) to evaluate the quality of studies and the Cochrane ROBANS tool to evaluate the risk of bias. Data extraction was done using piloted forms, and meta-analysis was done using the Mantel-Haenszel method. RESULTS: A total of 1088 citations were obtained with the search strategy. Eighteen studies matched inclusion and exclusion criteria and were included in the systematic review. The median quality of studies was 7/9 in NOS. There were fewer occurrences of head injury in obese individuals with an odd's ratio of 0.80% and 95% CI (0.69-0.93) with p = 0.004. More patients with BMI ≥ 30 had GCS ≤ 8 than patients with BMI < 30 with OR 1.08 (95%CI: 1.02-1.14). Obese patients had a more severe head injury (as per AIS) (58.9% vs 44.2%) and OR 1.83 (95%CI: 1.72-1.94), I2 = 87% and p < 0.00001. Length of ICU stay was more in obese individuals with a standard mean difference of 0.29 (95% CI: 0.03-0.55), I2 = 87%, p = 0.03. Similarly, obese individuals had a more extended hospital stay. There was no difference in mortality or ventilator days between obese and non-obese TBI patients. CONCLUSIONS: Obesity was associated with lower incidence and higher severity of head injury. However, there was no conclusive evidence that obesity confers protection from sustaining a head injury. Though the length of hospital and ICU stay were longer in obese individuals, the impact of obesity on mortality was not significant. There was no conclusive evidence for association of obesity with long term functional outcome or mortality following TBI.

2.
Oral Oncol ; 130: 105878, 2022 May 06.
Artigo em Inglês | MEDLINE | ID: mdl-35533510

RESUMO

OBJECTIVES: Radiation (ORNJ) and bisphosphonate-related (BRONJ) osteonecrosis of the jaw represent challenging entities to treat, with many patients requiring segmental resection and reconstruction with microvascular free tissue transfer (MFTT) in the setting of failed conservative therapy. Microvascular reconstruction is associated with higher post-operative complication rates when performed for advanced osteonecrosis versus oncologic defects. We hypothesize that basing antibiotic therapy on cultures obtained from the healthy bone marrow following resection during MFTT for ORNJ or BRONJ reduces rates of post-operative wound and surgical complications. MATERIALS AND METHODS: In a retrospective cohort study spanning January 2016 to October 2018, 44 patients undergoing MFTT for ORNJ or BRONJ were identified. Patients were categorized into two cohorts: residual healthy marrow culture (n = 11; RHM), treated with antibiotics guided by cultures from healthy appearing mandible, and all others (n = 33; AO), treated with antibiotics guided by cultures from resected necrotic bone or purulent drainage. Patient, reconstruction, and outcome variables were compared via appropriate statistical tools. RESULTS: 81.8% of the RHM cohort versus 24.2% of the AO cohort received long-term IV antibiotics. Rates of post-operative wound complications, including those necessitating operative management, were significantly lower in the RHM cohort. Rates of flap failure were similar across both groups. CONCLUSION: Administration of long-term IV antibiotics directed by native mandible cultures may decrease complication rates following MFTT for ORNJ or BRONJ by treating residual, smoldering infection. Concurrently, transplantation of well-vascularized free tissue likely improves antibiotic delivery. Findings are crucial for the development of a standardized treatment algorithm following microvascular reconstruction for advanced osteonecrosis.

3.
J Emerg Trauma Shock ; 15(1): 47-52, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35431488

RESUMO

The practice of emergency medicine has reached its cross roads. Emergency physicians (EPs) are managing many more time-dependent conditions, initiating complex treatments in the emergency department (ED), handling ethical and end of life care discussions upfront, and even performing procedures which used to be done only in critical care settings, in the resuscitation room. EPs manage a wide spectrum of patients, 24 h a day, which reflects the community and society they practice in. Besides the medical and "technical" issues to handle, they have to learn how to resolve confounding elements which their patients can present with. These may include social, financial, cultural, ethical, relationship, and even employment matters. EPs cannot overlook these, in order to provide holistic care. More and more emphasis is also now given to the social determinants of health. We, from the emergency medicine fraternity, are proposing a unique "BRAVE model," as a mnemonic to assist in the provision of point of care, adaptive leadership at the bedside in the ED. This represents another useful tool for use in the current climate of the ED, where patients have higher expectations, need more patient-centric resolution and handling of their issues, looming against the background of a more complex society and world.

4.
Indian J Surg Oncol ; 13(1): 68-80, 2022 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-35462658

RESUMO

Thyroid cancer is the most common endocrine malignancy. While surgery remains the mainstay of the treatment of all different histologies, for differentiated thyroid cancers, radioactive iodine also plays an important role in management. Once tumor becomes radio-iodine refractory, it needs systemic therapy. Earlier, these tumors had very dismal prognosis. However, with the advancement of technology and research, it has become clear now that thyroid cancer cells are driven by various mutations. Targeting these oncogenic drivers by various molecules have proven to be effective therapeutic strategy in thyroid cancer. Besides, as in other solid tumors, immunotherapy is also being evaluated in thyroid cancer. While these new therapeutic approaches have revolutionized the treatment on advanced/metastatic thyroid cancer, there are definite challenges which limit their use in common clinical practice. These challenges include higher treatment cost and lack of testing to identify the driver mutations. Moreover, there is still need for further research in thyroid cancers to identify oncogenic targets and agent to act upon them.

5.
Nat Commun ; 13(1): 2130, 2022 Apr 19.
Artigo em Inglês | MEDLINE | ID: mdl-35440101

RESUMO

A unique bifocal compound eye visual system found in the now extinct trilobite, Dalmanitina socialis, may enable them to be sensitive to the light-field information and simultaneously perceive both close and distant objects in the environment. Here, inspired by the optical structure of their eyes, we demonstrate a nanophotonic light-field camera incorporating a spin-multiplexed bifocal metalens array capable of capturing high-resolution light-field images over a record depth-of-field ranging from centimeter to kilometer scale, simultaneously enabling macro and telephoto modes in a snapshot imaging. By leveraging a multi-scale convolutional neural network-based reconstruction algorithm, optical aberrations induced by the metalens are eliminated, thereby significantly relaxing the design and performance limitations on metasurface optics. The elegant integration of nanophotonic technology with computational photography achieved here is expected to aid development of future high-performance imaging systems.


Assuntos
Óptica e Fotônica , Fotografação , Algoritmos , Olho , Redes Neurais de Computação
7.
Br J Neurosurg ; : 1-10, 2022 Feb 17.
Artigo em Inglês | MEDLINE | ID: mdl-35174747

RESUMO

BACKGROUND: Vestibular schwannoma is a common pathology encountered by neurosurgeons worldwide. Often vestibular schwannoma presents with obstructive hydrocephalus. Papilledema is present in 8% of the patients with vestibular schwannoma, primarily due to obstructive hydrocephalus. Hyperproteinorrhachia is believed to be responsible for papilledema in the absence of hydrocephalus in vestibular schwannoma. However, there is a paucity of literature on the mechanism of papilledema in vestibular schwannoma patients with hydrocephalus. OBJECTIVE: The aim of this study was to conduct a scoping review of scientific literature on papilledema in vestibular schwannoma patients without hydrocephalus. METHODS: Design: This was a systematic scoping review and critical appraisal. Literature Search from PubMed was done following PRISMA-ScR (Preferred Reporting Items for Systematic Reviews and Meta-Analyses Extension for Scoping Reviews) and Joanna Briggs Institute guidelines for conducting and reporting scoping reviews. RESULTS: A total of seven studies, including eight patients, were identified for inclusion in the review. The studies were heterogeneous in terms of reporting for various variables. All the included studies were case reports, with the earliest publication in 1954 and the latest publication in 2020. The mean age of the patients in the included studies was 35 years, with a minimum age of 20 years and maximum age of 64 years. Approximately 62.5% were females, and 37.5% were males in the included study. Only three studies have studied cerebrospinal fluid (CSF) proteins levels in these patients. CONCLUSIONS: There is paucity in literature and a lack of evidence to conclusively state hyperproteinorrhachia as an antecedent to the development of papilledema in vestibular schwannoma patients without hydrocephalus. Younger age and female gender are risk factors for developing papilledema in the absence of hydrocephalus in vestibular schwannoma patients. Brainstem compression due to the large size of vestibular schwannoma can still have a patent aqueduct of Sylvius and no obstruction to CSF flow. The development of papilledema in vestibular schwannoma is a complex interplay of multiple factors that must be studied comprehensively for complete understanding.

9.
3 Biotech ; 12(2): 55, 2022 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-35116217

RESUMO

Hippocampus is the significant component of the limbic lobe, which is further subdivided into the dentate gyrus and parts of Cornu Ammonis. It is the crucial region for learning and memory; its sub-regions aid in the generation of episodic memory. However, the hippocampus is one of the brain areas affected by Alzheimer's (AD). In the early stages of AD, the hippocampus shows rapid loss of its tissue, which is associated with the functional disconnection with other parts of the brain. In the progression of AD, atrophy of medial temporal and hippocampal regions are the structural markers in magnetic resonance imaging (MRI). Lack of sirtuin (SIRT) expression in the hippocampal neurons will impair cognitive function, including recent memory and spatial learning. Proliferation, differentiation, and migrations are the steps involved in adult neurogenesis. The microglia in the hippocampal region are more immunologically active than the other regions of the brain. Intrinsic factors like hormones, glia, and vascular nourishment are instrumental in the neural stem cell (NSC) functions by maintaining the brain's microenvironment. Along with the intrinsic factors, many extrinsic factors like dietary intake and physical activity may also influence the NSCs. Hence, pro-neurogenic lifestyle could delay neurodegeneration.

10.
Curr Pediatr Rev ; 2022 Feb 23.
Artigo em Inglês | MEDLINE | ID: mdl-35209834

RESUMO

Sweet's syndrome is a serious dermatological disorder characterized by a rapid onset of tender plaques or nodules, fever, joint pain, headache, oral and genital lesions. According to the clinical features and underlying causes, Sweet's syndrome is divided into three categories i.e. classical (or idiopathic), Malignancy-associated Sweet's syndrome, and Drug-induced Sweet's syndrome. It is multifactorial in etiology, and the exact cause is still undetermined. The diagnosis can be confirmed by the routine histopathologic evaluation of skin biopsy from the lesions. The first-line treatment options are topical and systemic steroids. To identify resources for this literature review, multiple databases like Medline/PubMed, Scopus, and Google Scholar were used. The relevant information was collected from various case reports, case series, reviews, meta-analyses and large clinical trials reporting clinical description, etiology, diagnosis and management of Sweet's syndrome. The aim of this narrative review is to discuss recent understandings related to Sweet's syndrome, both in terms of clinical presentation and management approach.

11.
OTO Open ; 6(1): 2473974X211070258, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35047718

RESUMO

OBJECTIVES: Osseous microvascular free tissue transfer (MFTT) is the gold standard for reconstruction for most segmental mandibulectomy defects. The most common osseous MFTT utilized in reconstruction is the fibular, scapular, and osteocutaneous radial forearm (OCRF) free flap. We evaluated postoperative bone union as well as clinical complications following MFTT and the impact of various patient and reconstructive characteristics, including type of osseous MFTT. STUDY DESIGN: Retrospective cohort study. SETTING: Tertiary care academic hospital. METHODS: This study examined patients who underwent osseous MFTT for mandibular defects from January 2017 to January 2019. RESULTS: An overall 144 osteotomies in 58 patients were evaluated. Of the 144 junctions, 28 (19.4%) showed radiographic nonunion. Patients who underwent preoperative (odds ratio [OR] = 0.30, P = .027) and postoperative (OR = 0.28, P = .003) radiation had a significantly lower bone union score. Time from surgery to postoperative imaging was associated with higher bone union scores (OR = 1.07, P = .024). When bone union scores were compared among types of MFTT, fibular (OR = 5.62, P = .008) and scapular (OR = 4.69, P = .043) MFTT had significantly higher scores than OCRF MFTT. Twelve (20.7%) patients had postoperative complications. There was no statistically significant correlation between clinical complications and various variables, including type of osseous MFTT. CONCLUSION: Pre- and postoperative radiation and time from surgery have an impact on bone union. Regarding the type of MFTT, fibular and scapular MFTT appeared to have higher bone union when compared with OCRF. There was no impact of bone union or type of osseous MFTT on clinical complications.

12.
Lab Chip ; 22(3): 592-604, 2022 02 01.
Artigo em Inglês | MEDLINE | ID: mdl-34985077

RESUMO

We report a two-inlet universal microfluidic gradient generator capable of generating gradient profiles of the functional form xp in the same device by controlling only the inlet flow rates. We have developed an analytical model to predict the inlet flow rates needed to generate a user-specified gradient profile at the outlet. We have validated this model by performing both COMSOL simulations and experiments. Our experiments show an excellent match between the target functions (x0.33, x1, x2 and x3) and the gradient profiles generated in this device. Unlike the universal gradient generators reported earlier, our device does not require changing the positions of the internal barriers for each new gradient profile, thereby making it easier for the user to operate this device.


Assuntos
Técnicas Analíticas Microfluídicas , Microfluídica
13.
Clin Lymphoma Myeloma Leuk ; 22(4): e221-e232, 2022 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-34750085

RESUMO

BACKGROUND: Core binding factor acute myeloid leukemia (CBF-AML) belongs to favorable risk group in AML. However, approximately 50% of patients with CBF-AML remain incurable and their outcomes are also determined by the various co-occurring mutations. Though, FMS-like tyrosine kinase-3(FLT3) mutation in AML is associated with poor survival, the prevalence and prognostic significance of FLT3 mutations among CBF-AML is unknown. PATIENTS AND METHODS: We performed a systematic review and meta-analysis to assess the prevalence of FLT3 mutations (ITD and TKD) among patients with CBF-AML. The pooled prevalence of FLT3 mutations was estimated for patients with CBF-AML, t(8;21) and Inv(16). Pooled odds ratio was calculated to compare the prevalence of various FLT3 mutations within the 2 subsets of CBF-AML. A random effects model was adopted for analysis when heterogenicity existed (Pheterogenicity< 0.05 or I2 > 50%). Otherwise, a fixed effects model was used. RESULTS: The pooled prevalence of any FLT3 mutations among patients with CBF-AML was available from 18 studies and was 13% (95% CI: 10%-16%; I2 = 79%). Comparison of prevalence of FLT3 mutations between the 2 subgroups of CBF-AML showed that patients with t(8;21) had a higher prevalence of FLT3-ITD [pooled odds ratio(OR): 2.23 (95% CI:1.41-3.53, P < .01)] and lower prevalence of FLT3-TKD [pooled OR: 0.29 (95% CI:0.19-0.44; P < .01)] compared to patients with Inv(16). Additionally, we have discussed the prognostic significance of FLT3 mutations in CBF-AML patients. CONCLUSION: The prevalence of FLT3-TKD mutation was commoner among Inv(16) AML while FLT3-ITD mutation was commoner among t(8;21) AML. Uniform reporting of outcomes is essential to understand the prognostic significance of FLT3 mutations among CBF-AML.


Assuntos
Leucemia Mieloide Aguda , Receptor 1 de Fatores de Crescimento do Endotélio Vascular , Fatores de Ligação ao Core/genética , Humanos , Leucemia Mieloide Aguda/genética , Mutação , Prevalência , Prognóstico , Proteínas Tirosina Quinases , Receptor 1 de Fatores de Crescimento do Endotélio Vascular/genética , Tirosina Quinase 3 Semelhante a fms/genética
14.
Genome Res ; 32(1): 55-70, 2022 01.
Artigo em Inglês | MEDLINE | ID: mdl-34903527

RESUMO

Human papillomavirus (HPV) causes 5% of all cancers and frequently integrates into host chromosomes. The HPV oncoproteins E6 and E7 are necessary but insufficient for cancer formation, indicating that additional secondary genetic events are required. Here, we investigate potential oncogenic impacts of virus integration. Analysis of 105 HPV-positive oropharyngeal cancers by whole-genome sequencing detects virus integration in 77%, revealing five statistically significant sites of recurrent integration near genes that regulate epithelial stem cell maintenance (i.e., SOX2, TP63, FGFR, MYC) and immune evasion (i.e., CD274). Genomic copy number hyperamplification is enriched 16-fold near HPV integrants, and the extent of focal host genomic instability increases with their local density. The frequency of genes expressed at extreme outlier levels is increased 86-fold within ±150 kb of integrants. Across 95% of tumors with integration, host gene transcription is disrupted via intragenic integrants, chimeric transcription, outlier expression, gene breaking, and/or de novo expression of noncoding or imprinted genes. We conclude that virus integration can contribute to carcinogenesis in a large majority of HPV-positive oropharyngeal cancers by inducing extensive disruption of host genome structure and gene expression.


Assuntos
Alphapapillomavirus , Proteínas Oncogênicas Virais , Neoplasias Orofaríngeas , Alphapapillomavirus/metabolismo , Carcinogênese , Humanos , Proteínas Oncogênicas Virais/genética , Neoplasias Orofaríngeas/genética , Papillomaviridae/genética , Papillomaviridae/metabolismo , Proteínas E7 de Papillomavirus/genética , Proteínas E7 de Papillomavirus/metabolismo , Integração Viral/genética
15.
Am J Otolaryngol ; 43(2): 103357, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-34972002

RESUMO

PURPOSE: Head and neck paragangliomas are slow growing tumors where observation has become more widely accepted. Tumor growth rate as well as predictors of increased tumor growth were analyzed with the goal to identify factors to better predict disease progression and counsel patients. MATERIALS AND METHODS: Multi-institutional retrospective cohort study from 2011 to 2020. RESULTS: 130 head and neck paragangliomas in 125 patients were analyzed. 38 were observed (30.4%), 16 radiated (12.8%), and 71 underwent surgery (56.8%). Surgical patients were significantly younger (p = 0.038) and with more genetically mediated paragangliomas (p = 0.026). Significantly more patients were asymptomatic in the observation group (p = 0.005). Of the 39 observed tumors, 43.6% (n = 17) grew with a tumor doubling time of 5.67 years. More than half of the observed paragangliomas had no growth. When examining symptoms postoperatively and at follow-up, the surgical cohort had significantly more worsening symptoms (p = 0.007) and new cranial neuropathies (p = 0.031). CONCLUSIONS: Head and neck paragangliomas have slow growth rates if they grow at all. Patients in the surgical cohort had more clinical symptoms at presentation and worsening postoperative symptoms.


Assuntos
Doenças dos Nervos Cranianos , Neoplasias de Cabeça e Pescoço , Paraganglioma , Progressão da Doença , Neoplasias de Cabeça e Pescoço/cirurgia , Humanos , Paraganglioma/cirurgia , Estudos Retrospectivos
16.
Ecancermedicalscience ; 15: 1287, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34824610

RESUMO

Sinonasal mucosal melanoma is a rare malignancy with limited treatment options and a poor prognosis. They are usually diagnosed at an advanced stage owing to their late and nonspecific clinical presentation. Here we present a case of relapsed refractory unresectable malignant melanoma involving the right nasal cavity managed with Oral Metronomic Chemotherapy (OMCT). A 75-year-old male patient was diagnosed with unresectable malignant melanoma involving the right nasal cavity and showed radiological progression after initial management with four cycles of Dacarbazine. He was then shifted to OMCT (Cyclophosphamide, Celecoxib and Tamoxifen), as immunotherapy could not be given due to financial constraints, on which he showed approximately 40% reduction in tumour size after 6 months. This result can have important clinical implications in resource constrained settings, where the use of immunotherapy is limited by great financial burden.

17.
Phys Fluids (1994) ; 33(10): 101701, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34737529

RESUMO

We discuss the temporal evolution of a cough jet of an infected subject in the context of the spread of COVID-19. Computations were carried out using large eddy simulation, and, in particular, the effect of the co-flow (5% and 10% of maximum cough velocity) on the evolution of the jet was quantified. The Reynolds number (Re) of the cough jet, based on the mouth opening diameter (D) and the average cough velocity, is 13 002. The time-varying inlet velocity profile of the cough jet is represented as a combination of gamma-probability-distribution functions. Simulations reveal the detailed structure of cough jet with and without a co-flow for the first time, to the best of our knowledge. The cough jet temporal evolution is similar to that of a continuous free-jet and follows the same routes of instability, as documented for a free-jet. The convection velocity of the cough jet decays with time and distance, following a power-law variation. The cough jet is observed to travel a distance of approximately 1.1 m in half a second. However, in the presence of 10% co-flow, the cough jet travels faster and covers the similar distance in just 0.33 s. Therefore, in the presence of a co-flow, the probability of transmission of COVID-19 by airborne droplets and droplet nuclei increases, since they can travel a larger distance. The cough jet without the co-flow corresponds to a larger volume content compared to that with the co-flow and spreads more within the same range of distance. These simulations are significant as they help to reveal the intricate structure of the cough jet and show that the presence of a co-flow can significantly augment the risk of infection of COVID-19.

18.
J Emerg Trauma Shock ; 14(3): 153-172, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34759634

RESUMO

The authors of this toolkit focus on children under the age of 18 comprising approximately 41% of the total population in India. This toolkit has been created with an objective to prepare, mitigate the effects of any surge of COVID-19 in our communities, and help to optimally utilize the scarce resources. The toolkit design suggests the manpower, equipment, laboratory support, training, consumables, and drugs for a 10-bedded pediatric emergency room, 25-bedded COVID pediatric intensive care unit, and 75-bedded COVID pediatric high dependency unit/ward as defined for a 100-bedded facility. A dedicated and detailed chapter is included to address the psychological needs of the children. These data can be modified for other department sizes based on the facilities, needs, local environment, and resources available.

19.
J Family Med Prim Care ; 10(9): 3219-3222, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34760733

RESUMO

BACKGROUND: For recognizing the initial stages of breast cancer, mammography is regarded as one of the best modalities and plays a crucial part to lessen morbidity and mortality. For collaborative studies and planning of preventive strategies, it is significant to have baseline data. Thus, in this survey, the frequency distribution of breast imaging reporting and data system (BIRADS) classification and breast consistencies was investigated during the mammographic screening program in the Gwalior region, India. MATERIAL AND METHODS: A descriptive, cross-sectional survey was conducted in the Gwalior region, India, in which 1,838 patients were screened with the aid of mammography. The mammography films were evaluated by a single radiologist who determined the BIRADS score, breast composition, and any other abnormal findings. After tabulating the data into MS Excel (MS Office version 2007 developed by Microsoft, Redmond, WA), descriptive analysis and Chi-square test were performed to determine the association between the BIRADS score and breast consistency and setting significance level at (below) 0.05. RESULTS: The most commonly found BIRADS score was score 1 (53.4%), followed by score 2 (20.4%), and score 5 was of the least frequency (1.3%). Similarly, the most common consistency found was fatty (48.2%) and the least common was heterogeneously dense (3.97%). The most BIRADS category of 0 was seen in heterogeneously dense (n = 22; 26%) followed by dense breast compositions (n = 18; 25%). The most common consistency found with known breast malignancy (BIRADS 6) patients was the extremely dense breast (n = 11; 40.7%). CONCLUSION: In this study, it was observed that about 57.3% of all the cases were categorized as BIRADS 1 and 20.8% as BIRADS 2.

20.
Phys Fluids (1994) ; 33(11): 111705, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34803361

RESUMO

A face shield is an important personal protective equipment to avoid the airborne transmission of COVID-19. We assess a transparent coating on a face shield that repels airborne respiratory droplets to mitigate the spread of COVID-19. The surface of the available face shield is hydrophilic and exhibits high contact angle hysteresis. The impacting droplets stick on it, resulting in an enhanced risk of fomite transmission of the disease. Further, it may get wetted in the rain, and moisture may condense on it in the presence of large humidity, which may blur the user's vision. Therefore, the present study aims to improve the effectiveness of a face shield. Our measurements demonstrate that the face shield, coated by silica nanoparticles solution, becomes superhydrophobic and results in a nominal hysteresis to the underlying surface. We employ high-speed visualization to record the impact dynamics of microliter droplets with a varying impact velocity and angle of attack on coated and non-coated surfaces. While the droplet on non-coated surface sticks to it, in the coated surface the droplets bounce off and roll down the surface, for a wide range of Weber number. We develop an analytical model and present a regime map of the bouncing and non-bouncing events, parametrized with respect to the wettability, hysteresis of the surface, and the Weber number. The present measurements provide the fundamental insights of the bouncing droplet impact dynamics and show that the coated face shield is potentially more effective in suppressing the airborne and fomite transmission.

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