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1.
J Cardiol ; 83(6): 377-381, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-37714265

RESUMO

BACKGROUND: Malignant cardiac neoplasms (MCNs), both primary and metastatic, are rare with few epidemiologic studies. METHODS: This retrospective study used the Healthcare Utilization Project/Nationwide Inpatient Sample database from 2002 to 2018 to evaluate the co-occurrences with other malignancies, and mortality of MCNs in the USA. RESULTS: The data contained 7207 weighted discharges of MCN. Median patient age was 51.4 years, 52.29 % were male, in-hospital mortality was 10.51 %, mean cost of hospitalization was $34,280 USD. Lung, mediastinum, and airways were the most common primary cancers associated with metastatic MCN. CONCLUSIONS: MCN are rare in the USA, however they carry a high in-hospital mortality, high morbidity, and hospital cost.


Assuntos
Neoplasias Cardíacas , Hospitalização , Humanos , Masculino , Estados Unidos/epidemiologia , Pessoa de Meia-Idade , Feminino , Estudos Retrospectivos , Neoplasias Cardíacas/epidemiologia , Mortalidade Hospitalar
2.
Ann Emerg Med ; 83(4): 385-393, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-37966412

RESUMO

STUDY OBJECTIVE: Bystander cardiopulmonary resuscitation (CPR) rates remain low in the United States. Training children is a proposed method to increase this rate, but data on the compression efficacy of US elementary school-aged children are scarce. We hypothesized that fourth and fifth graders could learn how to respond to cardiac arrests and provide effective chest compressions. METHODS: We conducted a nonrandomized before-and-after study with fourth- and fifth-grade elementary students. Two 2-hour CPR educational sessions were held. Two weeks later, skills were assessed using a de novo checklist, and manikin-analyzed compression effectiveness (dichotomized at 50% efficacy) was analyzed using Chi-squared tests. We used paired t tests to evaluate knowledge change on identical pre- and post-tests. Secondary analysis evaluated associations between compression effectiveness and grade, age, sex, and body mass index (BMI) using Chi-squared tests. RESULTS: Three hundred fifty-six students completed the study. The mean change in test scores measuring CPR knowledge increased from 8.2 to 9.3 (1.1, 95% confidence interval [CI] 0.9 to 1.2). Self-reported adequate CPR knowledge increased from 44% to 97% (odds ratio [OR] 44.17, 95% CI 12.62 to 154.62). Seventy-two percent of students completed >7/11 predefined resuscitation steps, and 76% delivered ≥50% effective compressions. Grade was significantly associated with achieving ≥50% effective compression (OR 2.02, 95% CI, 1.19 to 3.43). Age, BMI, and sex were not significantly associated with greater compression efficacy. CONCLUSION: Most students were able to learn hands-only CPR, apply their knowledge during a simulated cardiac arrest scenario, and deliver effective chest compressions. Students' confidence and willingness to perform CPR increased after the intervention.


Assuntos
Reanimação Cardiopulmonar , Parada Cardíaca , Criança , Humanos , Reanimação Cardiopulmonar/métodos , Parada Cardíaca/terapia , Manequins , Instituições Acadêmicas , Autorrelato , Estudantes , Estudos Controlados Antes e Depois
3.
Am Surg ; 90(3): 427-435, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-37703078

RESUMO

BACKGROUND: We hypothesized that the addition of a third-level trauma activation would improve outcomes by formalizing an evaluation process for patients in need of urgent evaluation who did not meet the criteria for full or partial trauma alert activation. METHODS: Admission records for all trauma patients admitted between 2000 and 2021 were obtained. The gamma alert trauma activation was implemented in 2011. A washout period of 6 months was used to account for adjustment to the new protocol. Propensity score matching was performed based on ISS scores, age, injury mechanism, and best-validated comorbidities to create a balanced patient distribution. Patients with missing data were excluded from this study. The association between era and outcomes was determined using logistic and linear regression analyses. RESULTS: The matched cohort was well balanced (SMD <.1, all balanced covariates) and included 18,572 patients. Patients in the gamma alert era had decreased ED dwell time, hospital length of stay, and intensive care unit (ICU) length of stay. Readmission rates and rates of upgrade to ICU status were reduced in the gamma alert era. This era was also associated with lower rates of renal failure, UTI, and pneumonia. There was no significant difference in mortality following implementation of the gamma alert. DISCUSSION: Implementation of the gamma alert was associated with an improvement in ED dwell times, fewer unplanned admissions to the ICU, decreased readmissions, and a reduction in other in-hospital events. We believe that this reflects improved triage of patients to the ICU and more effective care of trauma patients.


Assuntos
Centros de Traumatologia , Ferimentos e Lesões , Humanos , Estudos Retrospectivos , Unidades de Terapia Intensiva , Escala de Gravidade do Ferimento , Análise de Regressão , Tempo de Internação , Ferimentos e Lesões/diagnóstico , Ferimentos e Lesões/terapia
4.
Nat Commun ; 14(1): 4455, 2023 07 24.
Artigo em Inglês | MEDLINE | ID: mdl-37488113

RESUMO

Bone transport is a surgery-driven procedure for the treatment of large bone defects. However, challenging complications include prolonged consolidation, docking site nonunion and pin tract infection. Here, we develop an osteoinductive and biodegradable intramedullary implant by a hybrid tissue engineering construct technique to enable sustained delivery of bone morphogenetic protein-2 as an adjunctive therapy. In a male rat bone transport model, the eluting bone morphogenetic protein-2 from the implants accelerates bone formation and remodeling, leading to early bony fusion as shown by imaging, mechanical testing, histological analysis, and microarray assays. Moreover, no pin tract infection but tight osseointegration are observed. In contrast, conventional treatments show higher proportion of docking site nonunion and pin tract infection. The findings of this study demonstrate that the novel intramedullary implant holds great promise for advancing bone transport techniques by promoting bone regeneration and reducing complications in the treatment of bone defects.


Assuntos
Implantes Absorvíveis , Osteogênese , Masculino , Animais , Ratos , Bioensaio , Regeneração Óssea , Osseointegração
5.
Dev Psychobiol ; 65(5): e22396, 2023 07.
Artigo em Inglês | MEDLINE | ID: mdl-37338252

RESUMO

There is increasing concern about the potential effects of anesthesia exposure on the developing brain. The effects of relatively brief anesthesia exposures used repeatedly to acquire serial magnetic resonance imaging scans could be examined prospectively in rhesus macaques. We analyzed magnetic resonance diffusion tensor imaging (DTI) of 32 rhesus macaques (14 females, 18 males) aged 2 weeks to 36 months to assess postnatal white matter (WM) maturation. We investigated the longitudinal relationships between each DTI property and anesthesia exposure, taking age, sex, and weight of the monkeys into consideration. Quantification of anesthesia exposure was normalized to account for variation in exposures. Segmented linear regression with two knots provided the best model for quantifying WM DTI properties across brain development as well as the summative effect of anesthesia exposure. The resulting model revealed statistically significant age and anesthesia effects in most WM tracts. Our analysis indicated there were major effects on WM associated with low levels of anesthesia even when repeated as few as three times. Fractional anisotropy values were reduced across several WM tracts in the brain, indicating that anesthesia exposure may delay WM maturation, and highlight the potential clinical concerns with even a few exposures in young children.


Assuntos
Anestesia , Substância Branca , Masculino , Animais , Feminino , Substância Branca/diagnóstico por imagem , Macaca mulatta , Imagem de Tensor de Difusão/métodos , Encéfalo
6.
Sleep Med Clin ; 18(1): 31-38, 2023 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-36764784

RESUMO

Behavioral activation (BA) has long been long understood to be a particularly effective treatment for depression. Elements of BA are also to be found in components of insomnia treatment such as sleep restriction, stimulus control, and the setting of a morning routine. Although little research exists that examines the independent contribution of BA to the treatment of insomnia, it is reasonable to apportion some of the effect of cognitive-behavioral treatment of insomnia (CBT-I) to the implementation of BA whether that implementation is simply incidental to standard practice or more extensively deployed.


Assuntos
Terapia Cognitivo-Comportamental , Distúrbios do Início e da Manutenção do Sono , Humanos , Distúrbios do Início e da Manutenção do Sono/terapia , Sono , Resultado do Tratamento
7.
J Chem Phys ; 158(2): 024502, 2023 Jan 14.
Artigo em Inglês | MEDLINE | ID: mdl-36641388

RESUMO

Entropy scaling relates dynamic and thermodynamic properties by reducing the viscosity to a function of only the residual entropy. Molecular simulations are used to investigate the entropy scaling of the viscosity of three models of sodium chloride and five monovalent salts. Even though the correlation between the potential energy and the virial is weak, entropy scaling applies at liquid densities for all models and salts investigated. At lower densities, entropy scaling breaks down due to the formation of ion pairs and chains. Entropy scaling can be used to develop more extendable correlations for the dynamic properties of molten salts.

8.
Am Surg ; 89(11): 4668-4674, 2023 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-36120831

RESUMO

BACKGROUND: Patients with rib fractures have variable clinical courses and it is difficult to predict which patients will do poorly. Ideally this prediction would happen at the time of admission to facilitate effective triage. One scoring system devised to this end, is the Battle score. This study aims to evaluate the efficacy of the Battle score as triage tool, and to re-tool it for performance in an inpatient trauma setting. METHODS: A multivariate logistic regression model was trained on patients admitted to a level one trauma center with at least one rib fracture. A composite outcome was used to classify those who had poor outcomes. Eighteen candidate predictors were analyzed in univariate analysis, then the most promising fed into the logistic model until a triage score was built and internally validated by bootstrapping. RESULTS: Of the 838 patients who met the inclusion criteria, 145 (17.3%) patients had a defined poor outcome. The relevant predictors included in the final scoring system were number of ribs fractured, chest tube, pulmonary contusions, chronic obstructive pulmonary disease, and Glasgow coma score. Age was not found to be predictive. This score was found to have higher fidelity in predicting poor outcomes than the original Battle score (AUROC .858 vs .649.). DISCUSSION: An easy to calculate clinical scoring system was created to triage patients with rib fractures at the time of admission. Age may be of less importance than previously thought, while injury burden and history of lung disease may play a larger role.


Assuntos
Pneumopatias , Fraturas das Costelas , Traumatismos Torácicos , Humanos , Fraturas das Costelas/complicações , Fraturas das Costelas/terapia , Escala de Gravidade do Ferimento , Costelas , Estudos Retrospectivos
9.
Artigo em Inglês | MEDLINE | ID: mdl-38197035

RESUMO

This paper assesses and reports the experience of ten teams working to port, validate, and benchmark several High Performance Computing applications on a novel GPU-accelerated Arm testbed system. The testbed consists of eight NVIDIA Arm HPC Developer Kit systems, each one equipped with a server-class Arm CPU from Ampere Computing and two data center GPUs from NVIDIA Corp. The systems are connected together using InfiniBand interconnect. The selected applications and mini-apps are written using several programming languages and use multiple accelerator-based programming models for GPUs such as CUDA, OpenACC, and OpenMP offloading. Working on application porting requires a robust and easy-to-access programming environment, including a variety of compilers and optimized scientific libraries. The goal of this work is to evaluate platform readiness and assess the effort required from developers to deploy well-established scientific workloads on current and future generation Arm-based GPU-accelerated HPC systems. The reported case studies demonstrate that the current level of maturity and diversity of software and tools is already adequate for large-scale production deployments.

10.
J Am Acad Orthop Surg ; 30(21): e1366-e1373, 2022 11 01.
Artigo em Inglês | MEDLINE | ID: mdl-36026713

RESUMO

Gait analysis has expanding indications in orthopaedic surgery, both for clinical and research applications. Early work has been particularly helpful for understanding pathologic gait deviations in neuromuscular disorders and biomechanical imbalances that contribute to injury. Notable advances in image acquisition, health-related wearable devices, and computational capabilities for big data sets have led to a rapid expansion of gait analysis tools, enabling novel research in all orthopaedic subspecialties. Given the lower cost and increased accessibility, new gait analysis tools will surely affect the next generation of objective patient outcome data. This article reviews the basic principles of gait analysis, modern tools available to the common surgeon, and future directions in this space.


Assuntos
Procedimentos Ortopédicos , Ortopedia , Humanos , Análise da Marcha , Marcha , Fenômenos Biomecânicos
11.
Injury ; 53(9): 3059-3064, 2022 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-35623955

RESUMO

Trauma scoring systems were created to predict mortality and enhance triage capabilities. However, efficacy of scoring systems to predict mortality and accuracy of originally reported severity thresholds remains uncertain. A single-center, retrospective study was conducted at University of Virginia (UVA), an American College of Surgeons verified Level I trauma center. We compared four scoring systems: MGAP (Mechanism, Glasgow Coma Scale, Age, and arterial pressure), Injury Severity Score (ISS), New Injury Severity Score (NISS), and Trauma Related Injury Severity Score (TRISS) to predict in-hospital mortality and disposition from the emergency department to higher acuity level of care including mortality (i.e. operating room, intensive care unit, morgue) versus standard floor admission using area under the curve (AUC) for receiver operating characteristic analysis. Second, we examined sensitivity of these scores at standard thresholds to determine if adjustments were needed to minimize under-triage (sensitivity ≥95%). TRISS was the best predictor of mortality in a cohort of n = 16,265 with AUC of 0.920 (95% CI: 0.911-0.929, p<0.0001), followed by MGAP with AUC of 0.900 (95% CI: 0.889-0.911, p<0.0001), and finally ISS and NISS (0.830 (95% CI: 0.814-0.847) and 0.827 (95% CI: 0.809-0.844) respectively). NISS was the best predictor of high acuity disposition with an AUC of 0.729 (95% CI: 0.721-0.736, p<0.0001), followed by ISS with AUC of 0.714 (95% CI: 0.707-0.722, p<0.0001), and finally TRISS and MGAP (0.673 (95% CI: 0.665-0.682) and 0.613 (95% CI: 0.604-0.621) respectively (p<0.0001). At historic thresholds, no scoring system displayed adequate sensitivity to predict mortality, with values ranging from 73% for ISS to 80% for NISS. In conclusion, in the reported study cohort, TRISS was the best predictor of mortality while NISS was the best predictor of high acuity disposition. We also stress updating scoring system thresholds to achieve ideal sensitivity, and investigating how scoring systems derived to predict mortality perform when predicting indicators of morbidity such as disposition from the emergency department.


Assuntos
Hospitais , Ferimentos e Lesões , Humanos , Escala de Gravidade do Ferimento , Valor Preditivo dos Testes , Curva ROC , Estudos Retrospectivos , Índices de Gravidade do Trauma , Ferimentos e Lesões/terapia
12.
iScience ; 25(5): 104229, 2022 May 20.
Artigo em Inglês | MEDLINE | ID: mdl-35494239

RESUMO

This review presents bioprinting methods, biomaterials, and printing strategies that may be used for composite tissue constructs for musculoskeletal applications. The printing methods discussed include those that are suitable for acellular and cellular components, and the biomaterials include soft and rigid components that are suitable for soft and/or hard tissues. We also present strategies that focus on the integration of cell-laden soft and acellular rigid components under a single printing platform. Given the structural and functional complexity of native musculoskeletal tissue, we envision that hybrid bioprinting, referred to as hybprinting, could provide unprecedented potential by combining different materials and bioprinting techniques to engineer and assemble modular tissues.

13.
Curr Sleep Med Rep ; 7(4): 213-220, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34804765

RESUMO

Purpose of Review: Response to cognitive-behavioral therapy for insomnia (CBT-I) is variable across individuals, and specialty insomnia clinics that provide CBT-I are few. To personalize insomnia treatments and maximize the cost-effectiveness of CBT-I, this paper reviews the conceptual model and content of CBT-I and the predictors of adherence/response to CBT-I as the basis for understanding who is most likely to benefit from CBT-I. Recent Findings: Specific patient-related attributes that predict benefit from CBT-I include (1) presence of maladaptive behaviors that serve as perpetuating factors of insomnia; (2) greater motivation to pursue therapy and higher treatment expectancies regarding CBT-I; (3) reduced use of hypnotics; (4) longer sleep duration; and (5) adequately treated psychiatric comorbidities. Summary: People presenting with chronic insomnia and these attributes may warrant prioritization in referral to behavioral insomnia clinics. Conversely, those who do not have such favorable characteristics may require interventions that address modifiable factors associated with poor adherence/response to CBT-I.

14.
Ann Surg ; 274(4): 572-580, 2021 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-34506312

RESUMO

OBJECTIVE: Value is defined as health outcomes important to patients relative to cost of achieving those outcomes: Value = Quality/Cost. For inguinal hernia repair, Level 1 evidence shows no differences in long-term functional status or recurrence rates when comparing surgical approaches. Differences in value reside within differences in cost. The aim of this study is to compare the value of different surgical approaches to inguinal hernia repair: Open (Open-IH), Laparoscopic (Lap-IH), and Robotic (R-TAPP). METHODS: Variable and fixed hospital costs were compared among consecutive Open-IH, Lap-IH, and R-TAPP repairs (100 each) performed in a university hospital. Variable costs (VC) including direct materials, labor, and variable overhead ($/min operating room [OR] time) were evaluated using Value Driven Outcomes, an internal activity-based costing methodology. Variable and fixed costs were allocated using full absorption costing to evaluate the impact of surgical approach on value. As cost data is proprietary, differences in cost were normalized to Open-IH cost. RESULTS: Compared to Open-IH, VC for Lap-IH were 1.02X higher (including a 0.81X reduction in cost for operating room [OR] time). For R-TAPP, VC were 2.11X higher (including 1.36X increased costs for OR time). With allocation of fixed cost, a Lap-IH was 1.03X more costly, whereas R-TAPP was 3.18X more costly than Open-IH. Using equivalent recurrence as the quality metric in the value equation, Lap-IH decreases value by 3% and R-TAPP by 69% compared to Open-IH. CONCLUSIONS: Use of higher cost technology to repair inguinal hernias reduces value. Incremental health benefits must be realized to justify increased costs. We expect payors and patients will incorporate value into payment decisions.


Assuntos
Hérnia Inguinal/cirurgia , Herniorrafia/economia , Custos Hospitalares , Laparoscopia/economia , Procedimentos Cirúrgicos Robóticos/economia , Análise Custo-Benefício , Hérnia Inguinal/economia , Humanos , Recuperação de Função Fisiológica , Recidiva , Telas Cirúrgicas/economia , Resultado do Tratamento
15.
J Appl Lab Med ; 6(5): 1293-1298, 2021 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-34136903

RESUMO

BACKGROUND: Tacrolimus has a low therapeutic index requiring strict control of whole blood concentrations. Although random access immunoassay platforms exist that rapidly provide quantitative values for tacrolimus, LC-MS/MS may provide more accurate quantitation. However, batch testing in many LC-MS/MS assays is not efficient, particularly when testing patients suspected of having tacrolimus toxicity. Extending calibration curve stability beyond the traditionally accepted single batch may facilitate improved turnaround time and reduce testing costs. A 24-h extended calibration of LC-MS/MS tacrolimus was designed and validated to reduce calibrator usage, improve turnaround time, and provide a more efficient workflow for urgent requests. METHODS: Patient samples included in the study were extracted and assayed with coextracted calibrators and quality control in real time. The same patient samples were extracted again 24 h later without coextracted calibrators. The data acquired from the second patient sample extraction was applied to the original calibration curve acquired 24 h prior and compared to the data for the same samples coextracted with calibrators, creating a value set utilizing extended curve stability. RESULTS: A linear regression compared the results using the extended curve to the results of the coextracted acquisitions. This yielded a strong correlation between the 2 data populations, with a slope of 1.0061 and a correlation coefficient of >0.95. The average bias between original patient values and patient values 24 h later was 3.4% across all patient samples. CONCLUSIONS: Patient tacrolimus values were comparable when extracted within 24 h of calibration versus values coextracted with calibrators. Demonstrating comparability within 24 h of calibration allows the laboratory to provide rapid turnaround time for urgent samples without the need for an entirely new calibration curve.


Assuntos
Tacrolimo , Espectrometria de Massas em Tandem , Calibragem , Cromatografia Líquida , Monitoramento de Medicamentos , Humanos
16.
Br J Anaesth ; 126(4): 845-853, 2021 04.
Artigo em Inglês | MEDLINE | ID: mdl-33549320

RESUMO

BACKGROUND: Non-human primates are commonly used in neuroimaging research for which general anaesthesia or sedation is typically required for data acquisition. In this analysis, the cumulative effects of exposure to ketamine, Telazol® (tiletamine and zolazepam), and the inhaled anaesthetic isoflurane on early brain development were evaluated in two independent cohorts of typically developing rhesus macaques. METHODS: Diffusion MRI scans were analysed from 43 rhesus macaques (20 females and 23 males) at either 12 or 18 months of age from two separate primate colonies. RESULTS: Significant, widespread reductions in fractional anisotropy with corresponding increased axial, mean, and radial diffusivity were observed across the brain as a result of repeated anaesthesia exposures. These effects were dose dependent and remained after accounting for age and sex at time of exposure in a generalised linear model. Decreases of up to 40% in fractional anisotropy were detected in some brain regions. CONCLUSIONS: Multiple exposures to commonly used anaesthetics were associated with marked changes in white matter microstructure. This study is amongst the first to examine clinically relevant anaesthesia exposures on the developing primate brain. It will be important to examine if, or to what degree, the maturing brain can recover from these white matter changes.


Assuntos
Anestesia Geral/efeitos adversos , Encéfalo/efeitos dos fármacos , Encéfalo/diagnóstico por imagem , Substância Branca/efeitos dos fármacos , Substância Branca/diagnóstico por imagem , Animais , Animais Recém-Nascidos , Encéfalo/metabolismo , Imagem de Tensor de Difusão/tendências , Feminino , Macaca mulatta , Masculino
17.
Psychoneuroendocrinology ; 124: 105068, 2021 02.
Artigo em Inglês | MEDLINE | ID: mdl-33260081

RESUMO

Adolescence is a transitional period between childhood and adulthood characterized by significant changes in global and regional brain tissue volumes. It is also a period of increasing vulnerability to psychiatric illness. The relationship between these patterns and increased levels of circulating sex steroids during adolescence remains unclear. The objective of the current study was to determine whether gonadectomy, prior to puberty, alters adolescent brain development in male rhesus macaques. Ninety-six structural MRI scans were acquired from 12 male rhesus macaques (8 time points per animal over a two-year period). Six animals underwent gonadectomy and 6 animals underwent a sham operation at 29 months of age. Mixed-effects models were used to determine whether gonadectomy altered developmental trajectories of global and regional brain tissue volumes. We observed a significant effect of gonadectomy on the developmental trajectory of prefrontal gray matter (GM), with intact males showing peak volumes around 3.5 years of age with a subsequent decline. In contrast, prefrontal GM volumes continued to increase in gonadectomized males until the end of the study. We did not observe a significant effect of gonadectomy on prefrontal white matter or on any other global or regional brain tissue volumes, though we cannot rule out that effects might be detected in a larger sample. Results suggest that the prefrontal cortex is more vulnerable to gonadectomy than other brain regions.


Assuntos
Encéfalo , Maturidade Sexual , Animais , Encéfalo/diagnóstico por imagem , Castração , Substância Cinzenta/diagnóstico por imagem , Macaca mulatta , Imageamento por Ressonância Magnética , Masculino
18.
J Chem Phys ; 153(2): 024501, 2020 Jul 14.
Artigo em Inglês | MEDLINE | ID: mdl-32668951

RESUMO

Scaled-charge models have been recently introduced for molecular simulations of electrolyte solutions and molten salts to attempt to implicitly represent polarizability. Although these models have been found to accurately predict electrolyte solution dynamic properties, they have not been tested for coexistence properties, such as the vapor pressure of the melt. In this work, we evaluate the vapor pressure of a scaled-charge sodium chloride (NaCl) force field and compare the results against experiments and a non-polarizable full-charge force field. The scaled-charge force field predicts a higher vapor pressure than found in experiments, due to its overprediction of the liquid-phase chemical potential. Reanalyzing the trajectories generated from the scaled-charge model with full charges improves the estimation of the liquid-phase chemical potential but not the vapor pressure.

19.
J Chem Theory Comput ; 16(9): 5736-5746, 2020 Sep 08.
Artigo em Inglês | MEDLINE | ID: mdl-32709204

RESUMO

Molten alkali-metal carbonates and hydroxides play important roles in the molten carbonate fuel cell and in Earth's geochemistry. Molecular simulations allow us to study these systems at extreme conditions without the need for difficult experimentation. Using a genetic algorithm to fit ab intio molecular dynamics-computed densities and radial distribution functions, as well as experimental enthalpies of formation, we derive new classical force fields able to accurately predict liquid chemical potentials. These fitting properties were chosen to ensure accurate liquid phase structure and energetics. Although the predicted dynamics is slow when compared to experiments, in general the trends in dynamic properties across different systems still hold true. In addition, these newly parametrized force fields can be extended to the molten carbonate-hydroxide mixtures by using standard combining rules.

20.
Cureus ; 12(4): e7843, 2020 Apr 26.
Artigo em Inglês | MEDLINE | ID: mdl-32483494

RESUMO

Pediatric fractures are a common injury, and treatment often includes cast immobilization. For pediatric patients being treated in a cast, cast damage is among the most common reasons patients return to the emergency room. The figure-of-eight wrapping technique interdigitates layers of fiberglass which may create a stronger cast. The aim of this study was to assess the strength of the figure-of-eight wrapping technique in comparison to the spiral wrapping technique. A total of 10 casts were wrapped with a three-inch fiberglass using the spiral technique and 10 casts were wrapped using the figure-of-eight technique. Each cast was then subjected to a three-point bending test and loaded until failure using an Instron machine. The figure-of-eight technique had an average load to failure of 278.2 + 27.6 N/mm which was similar to the spiral technique's load to failure of 281.2 + 25.4 N/mm (p=0.795). Prior to normalizing for thickness, the load to failure of the figure-of-eight technique was 949.8 + 109.5 N, which was significantly higher than the spiral technique of 868.2 + 65.1 N (p=0.038). The figure-of-eight casts were slightly thicker than the spiral casts (average 0.3 mm, p=0.004). This suggests that the thickness of the fiberglass cast may improve the strength. The figure-of-eight wrapping technique had similar biomechanical characteristics to spiral wrapping techniques. Providers should wrap in whichever technique they feel most comfortable performing as there is no difference in strength of the cast. If a stronger cast is desired, then thickness of the cast can be increased.

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