Experimental and Theoretical Investigation on Heat Transfer Enhancement in Micro Scale Using Helical Connectors.

Microscale electronics have become increasingly more powerful, requiring more efficient cooling systems to manage the higher thermal loads. To meet this need, current research has been focused on overcoming the inefficiencies present in typical thermal management systems due to low Reynolds numbers within microchannels and poor physical properties of the working fluids. For the first time, this research investigated the effects of a connector with helical geometry on the heat transfer coefficient at low Reynolds numbers. The introduction of a helical connector at the inlet of a microchannel has been experimentally tested and results have shown that this approach to flow augmentation has a great potential to increase the heat transfer capabilities of the working fluid, even at low Reynolds numbers. In general, a helical connector can act as a stabilizer or a mixer, based on the characteristics of the connector for the given conditions. When the helical connector acts as a mixer, secondary flows develop that increase the random motion of molecules and possible nanoparticles, leading to an enhancement in the heat transfer coefficient in the microchannel. Otherwise, the heat transfer coefficient decreases. It is widely known that introducing nanoparticles into the working fluids has the potential to increase the thermal conductivity of the base fluid, positively impacting the heat transfer coefficient; however, viscosity also tends to increase, reducing the random motion of molecules and ultimately reducing the heat transfer capabilities of the working fluid. Therefore, optimizing the effects of nanoparticles characteristics while reducing viscous effects is essential. In this study, deionized water and deionized water-diamond nanofluid at 0.1 wt% were tested in a two-microchannel system fitted with a helical connector in between. It was found that the helical connector can make a great heat transfer coefficient enhancement in low Reynolds numbers when characteristics of geometry are optimized for given conditions.

The Effects of Wastewater Reuse on Smallmouth Bass (Micropterus dolomieu) Relative Abundance in the Shenandoah River Watershed, USA.

Municipal and industrial wastewater effluent is an important source of water for lotic systems, especially during periods of low flow. The accumulated wastewater effluent flows-expressed as a percentage of total streamflow (ACCWW%)-contain chemical mixtures that pose a risk to aquatic life; fish may be particularly vulnerable when chronically exposed. Although there has been considerable focus on individual-level effects of exposure to chemical mixtures found in wastewater effluent, scaling up to population-level effects remains a challenging component needed to better understand the potential consequences of exposure in wild populations. This may be particularly important under a changing climate in which wastewater reuse could be essential to maintain river flows. We evaluated the effects of chronic exposure to wastewater effluent, as measured by ACCWW%, on the relative abundance of young-of-year (YOY), juvenile, and adult smallmouth bass (Micropterus dolomieu) populations in the Shenandoah River Watershed (USA). We found that increases in ACCWW% in the previous year and during the prespawn period were negatively correlated with the relative abundance of YOY, resulting in an average 41% predicted decrease in abundance (range = 0.5%-94% predicted decrease in abundance). This lagged effect suggests that adult fish reproductive performance may be compromised by chemical exposure during periods of high ACCWW%. No relationships between ACCWW% and juvenile or adult relative abundance were found, suggesting that negative effects of ACCWW% on YOY abundance may be offset due to compensatory mechanisms following higher ACCWW% exposure. Understanding the effects of wastewater effluent exposure at multiple levels of biological organization will help in the development of management strategies aimed at protecting aquatic life. Environ Toxicol Chem 2024;43:1138-1148. © 2024 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.

Venovenous extracorporeal membrane oxygenation in patients with traumatic brain injuries and severe respiratory failure: A single-center retrospective analysis.

BACKGROUND: Venovenous extracorporeal membrane oxygenation (VV ECMO) can support trauma patients with severe respiratory failure. Use in traumatic brain injury (TBI) may raise concerns of worsening complications from intracranial bleeding. However, VV ECMO can rapidly correct hypoxemia and hypercarbia, possibly preventing secondary brain injury. We hypothesize that adult trauma patients with TBI on VV ECMO have comparable survival with trauma patients without TBI. METHODS: A single-center, retrospective cohort study involving review of electronic medical records of trauma admissions between July 1, 2014, and August 30, 2022, with discharge diagnosis of TBI who were placed on VV ECMO during their hospital course was performed. RESULTS: Seventy-five trauma patients were treated with VV ECMO; 36 (48%) had TBI. Of those with TBI, 19 (53%) had a hemorrhagic component. Survival was similar between patients with and without a TBI (72% vs. 64%, p = 0.45). Traumatic brain injury survivors had a higher admission Glasgow Coma Scale (7 vs. 3, p < 0.001) than nonsurvivors. Evaluation of prognostic scoring systems on initial head computed tomography demonstrated that TBI VV ECMO survivors were more likely to have a Rotterdam score of 2 (62% vs. 20%, p = 0.03) and no survivors had a Marshall score of ≥4. Twenty-nine patients (81%) had a repeat head computed tomography on VV ECMO with one incidence of expanding hematoma and one new focus of bleeding. Neither patient with a new/worsening bleed received anticoagulation. Survivors demonstrated favorable neurologic outcomes at discharge and outpatient follow-up, based on their mean Rancho Los Amigos Scale (6.5; SD, 1.2), median Cerebral Performance Category (2; interquartile range, 1-2), and median Glasgow Outcome Scale-Extended (7.5; interquartile range, 7-8). CONCLUSION: In this series, the majority of TBI patients survived and had good neurologic outcomes despite a low admission Glasgow Coma Scale. Venovenous extracorporeal membrane oxygenation may minimize secondary brain injury and may be considered in select patients with TBI. LEVEL OF EVIDENCE: Prognostic and Epidemiological; Level IV.

Direct Discharge from the Critical Care Resuscitation Unit: Results from a Longitudinal Assessment.

Background: The critical care resuscitation unit (CCRU) facilitates interhospital transfer (IHT) of critically ill patients for immediate interventions. Due to these patients' acuity, it is uncommon for patients to be directly discharged home from this unit, but it does happen on occasion. Since there is no literature regarding outcomes of patients being discharged from a resuscitation unit, our study investigated these patients' outcome at greater than 12 months after being discharged directly from the CCRU. Methods: We performed a retrospective cohort study of all adult patients directly discharged from the CCRU between January 01, 2017, and December 31, 2020. The primary outcome was number of ED visits or hospitalizations within 6 months. Secondary outcomes were number of ED visits or hospitalizations within 6, 12, and >12 months from CCRU discharge. Results: We analyzed 145 patients' records. Mean age was 56 (standard deviation [SD] ± 19), with a majority being male (72%) and Caucasian (58%). The most common discharge destination was home (139 patients, 96% of total subjects) versus hospice (2%) or nursing facilities (2%). Most patients (55%) did not have any hospital revisits within the first 6 months of discharge, while 31% had 1-2 revisits, and 14% had ≥3 revisits. The most common discharge diagnoses were soft tissue infection (16.5%), aortic dissection (14%), and stroke (11%). Factors which were associated with a greater likelihood of any return hospital visit within 6 months receiving mechanical ventilation during CCRU stay (coefficient -2.23, 95% CI 0.01-0.87, P=0.036), while high hemoglobin on CCRU discharge was associated with no ED revisit (coeff. 0.42, 95% CI 1.15-2.06, P=0.004). Conclusions: Most patients who were discharged from the CCRU did not require any hospital revisits in the first 6 months. Requiring mechanical ventilation and having soft tissue infection were associated with high unplanned hospital revisits following discharge. Further research is needed to validate these findings.

Advances in Trauma Ultrasound.

Bedside ultrasound assessment has become a routine aspect of care in trauma resuscitation and the critical care setting. Although early research was focused on its role in blunt trauma, it has shown utility in the assessment of penetrating trauma by rapidly identifying hemopericardium and facilitating appropriate intraoperative management. In addition, ultrasound is a reliable test in identifying hemopneumothorax or diaphragmatic injuries. The Rapid Ultrasound in Shock and Hypotension and the Focused Rapid Echocardiographic Examination can diagnose etiologies of shock and guide resuscitation in the critically ill patient. Finally, the role of transesophageal echocardiography is expanding in the trauma setting as more research emerges.

The surgical outcome of multilevel anterior cervical discectomy and fusion in myelopathic elderly and younger patients.

The elderly population has an increased risk of degenerative cervical myelopathy due to multilevel disease, causing motor and sensory dysfunctions and a poor quality of life. Multilevel anterior cervical discectomy and fusion (ACDF) is an alternative surgical treatment option, but has a perceived higher risk of complications. The goal of this study is to report the outcome. We retrospectively reviewed patients from 2006 to 2019 undergoing multilevel ACDF for degenerative cervical myelopathy and compared outcomes and complications between elder patients (aged 70 and above) and younger patients (below 70). The patients' comorbidities, and postoperative complications, radiographic parameters such as C2-C7 Cobb angle, C2-C7 sagittal vertical axis, inter-body height of surgical levels and fusion rate were recorded. Japanese Orthopaedic Association (JOA) score and modified Odom's score were collected. Included were 18 elderly (mean age 74, range 70-87) and 45 young patients (mean age 56, range 43-65) with a follow-up of 43.8 and 55.5 months respectively. Three-level ACDF was the most common. The ratios of ASA class III patients were 94.4% and 48.9% (p < 0.001). The Charlson comorbidity indexes were 4.3 ± 1.03 and 2.1 ± 1.11 (p < 0.001). The average lengths of hospital stays were 4.9 and 4.6 days. Eleven patients (61.1%) in the elderly group experienced at least one short-term complication, compared with 16 patients (35.6%) in the younger group (p < 0.05). The middle-term complications were comparable (22.2% and 20.0%). The JOA score, recovery rate and modified Odom score showed comparable result between groups. Despite its extensiveness, multilevel ACDF is feasible for the elder patients with good clinical outcome and fusion rate. When compared to younger cohort, there is a trend of lower preoperative JOA score and recovery rate. The short-term complication rate is higher in the elderly group.

Identification of an Infected Urachal Cyst Using Point-of-Care Ultrasound.

ABSTRACT: This case describes a 6-year-old girl who presented to the pediatric emergency department with 3 days of fever and suprapubic pain in the setting of 1 month of worsening, dull abdominal pain. On presentation, she had a tender, erythematous, and fluctuant mass on her lower abdomen. Point-of-care ultrasound was used to identify an abnormal fluid collection anterior to her bladder, suspicious for an infected urachal cyst. In this case, point-of-care ultrasound helped identify this uncommon finding in a timely fashion, which expedited definitive care and prevented unnecessary exposure to ionizing radiation.

Linking Altered Flow Regimes to Biological Condition: an Example Using Benthic Macroinvertebrates in Small Streams of the Chesapeake Bay Watershed.

Regionally scaled assessments of hydrologic alteration for small streams and its effects on freshwater taxa are often inhibited by a low number of stream gages. To overcome this limitation, we paired modeled estimates of hydrologic alteration to a benthic macroinvertebrate index of biotic integrity data for 4522 stream reaches across the Chesapeake Bay watershed. Using separate random-forest models, we predicted flow status (inflated, diminished, or indeterminant) for 12 published hydrologic metrics (HMs) that characterize the main components of flow regimes. We used these models to predict each HM status for each stream reach in the watershed, and linked predictions to macroinvertebrate condition samples collected from streams with drainage areas less than 200 km2. Flow alteration was calculated as the number of HMs with inflated or diminished status and ranged from 0 (no HM inflated or diminished) to 12 (all 12 HMs inflated or diminished). When focused solely on the stream condition and flow-alteration relationship, degraded macroinvertebrate condition was, depending on the number of HMs used, 3.8-4.7 times more likely in a flow-altered site; this likelihood was over twofold higher in the urban-focused dataset (8.7-10.8), and was never significant in the agriculture-focused dataset. Logistic regression analysis using the entire dataset showed for every unit increase in flow-alteration intensity, the odds of a degraded condition increased 3.7%. Our results provide an indication of whether altered streamflow is a possible driver of degraded biological conditions, information that could help managers prioritize management actions and lead to more effective restoration efforts.

Iatrogenic biological fracture of the cervical spine during gradual halo traction for kyphotic deformity correction: case report.

BACKGROUND: Severe kyphotic deformities carry high risk for neurological injuries as osteotomies are often required for correction. Surgeons often utilize a staged approach for dealing with these conditions starting with a period of halo traction to stretch tight soft tissues and partially correct the deformity, followed by surgery. Halo traction is a relatively safe procedure and complications are uncommon. We report a unique case of iatrogenic fracture of the cervical spine during gradual halo traction for deformity correction of a severe cervical kyphosis. CASE PRESENTATION: An 80-year-old female with previous cervical spine tuberculosis infection and C5-C6 anterior spinal fusion developed severe cervical kyphosis of 64° from C2-C6 and neck pain requiring deformity correction surgery. Gradual increase in traction weight was applied, aiming for a maximum traction weight of 45 pounds or half body weight. During the 1st stage halo-gravity traction, sudden neck pain and a loud cracking sound was witnessed during increase of the traction weight to 14 pounds. Imaging revealed a fracture through the C4 and reduction in kyphosis deformity to 11° from C2-C6. There was no neurological deficit. No further traction was applied and the patient underwent an in-situ occipital to T3 fusion without osteotomies. At 3-year follow-up, the patient was symptom-free and radiographs showed solid fusion and maintenance of alignment. CONCLUSIONS: Iatrogenic fracture may occur with halo traction. Elderly patients with osteoporotic and diseased bone should be closely monitored during the treatment. A fracture without complications was a fortunate complication as the patient was able to avoid any high-risk osteotomies for deformity correction. LEVEL OF EVIDENCE: IV.