Observation and Isochoric Thermodynamic Analysis of Partially Water-Filled 1.32 and 1.45 nm Diameter Carbon Nanotubes.

Recent measurements of fluids under extreme confinement, including water within narrow carbon nanotubes, exhibit marked deviations from continuum theoretical descriptions. In this work, we generate precise carbon nanotube replicates that are filled with water, closed from external mass transfer, and studied over a wide temperature range by Raman spectroscopy. We study segments that are empty, partially filled, and completely filled with condensed water from -80 to 120 °C. Partially filled, nanodroplet states contain submicron vapor-like and liquid-like domains and are analyzed using a Clausius-Clapeyron-type model, yielding heats of condensation of water inside closed 1.32 nm diameter carbon nanotubes (3.32 ± 0.10 kJ/mol and 3.72 ± 0.11 kJ/mol) and 1.45 nm diameter carbon nanotubes (3.50 ± 0.07 kJ/mol) that are lower than the bulk enthalpy of vaporization and closer to the bulk enthalpy of fusion. Favored partial filling fractions are calculated, highlighting the effect of subnanometer changes in confining diameter on fluid properties and suggesting the promise of molecular engineering of nanoconfined liquid/vapor interfaces for water treatment or membrane distillation.

Discretized hexagonal boron nitride quantum emitters and their chemical interconversion.

Quantum emitters in two-dimensional hexagonal boron nitride (hBN) are of significant interest because of their unique photophysical properties, such as single-photon emission at room temperature, and promising applications in quantum computing and communications. The photoemission from hBN defects covers a wide range of emission energies but identifying and modulating the properties of specific emitters remain challenging due to uncontrolled formation of hBN defects. In this study, more than 2000 spectra are collected consisting of single, isolated zero-phonon lines (ZPLs) between 1.59 and 2.25 eV from diverse sample types. Most of ZPLs are organized into seven discretized emission energies. All emitters exhibit a range of lifetimes from 1 to 6 ns, and phonon sidebands offset by the dominant lattice phonon in hBN near 1370 cm-1. Two chemical processing schemes are developed based on water and boric acid etching that generate or preferentially interconvert specific emitters, respectively. The identification and chemical interconversion of these discretized emitters should significantly advance the understanding of solid-state chemistry and photophysics of hBN quantum emission.

Management and referral patterns for new-onset chronic cough in primary care patients.

Background: The diagnosis and management of chronic cough in primary care is challenging despite it being one of the most common chronic conditions. Objective: Clinical characterization of patients with new-onset chronic cough in the primary care setting. Methods: This was a retrospective study of adult patients (ages ≥ 18 years) with at least three visits with primary care providers (PCP) for new-onset cough, with at least 8 weeks between the first and third visits, within a tertiary-care center and affiliated clinics between January 1, 2010, and January 1, 2019 (N = 174). We calculated the frequency of primary care visits, diagnostic testing, specialist referrals, and prescribed medications up to 18 months after the third visit with a PCP for cough. Results: Of 174 patients who met the criteria of new-onset chronic cough, >50% had four or more primary care visits related to cough. Despite that, 91 (52.3%) did not receive a referral to a specialist, and 41 (23.5%) did not receive an order for a chest radiograph during the evaluation of the chronic cough. Antibiotics and systemic corticosteroids were prescribed to 106 (61%) and 63 (36%) of the patients, respectively, and 20% were prescribed opiates. No patients were prescribed central-neuromodulating agents, and angiotensin-converting enzyme inhibitors were discontinued in 48% of the patients who were taking them (12/25). Conclusion: We found considerable heterogeneity and discrepancies with clinical guideline recommendations in patients who presented with new chronic cough. There is a substantial unmet need to study chronic cough in the primary care setting to inform important stakeholders.

Gas Separations using Nanoporous Atomically Thin Membranes: Recent Theoretical, Simulation, and Experimental Advances.

Porous graphene and other atomically thin 2D materials are regarded as highly promising membrane materials for high-performance gas separations due to their atomic thickness, large-scale synthesizability, excellent mechanical strength, and chemical stability. When these atomically thin materials contain a high areal density of gas-sieving nanoscale pores, they can exhibit both high gas permeances and high selectivities, which is beneficial for reducing the cost of gas-separation processes. Here, recent modeling and experimental advances in nanoporous atomically thin membranes for gas separations is discussed. The major challenges involved, including controlling pore size distributions, scaling up the membrane area, and matching theory with experimental results, are also highlighted. Finally, important future directions are proposed for real gas-separation applications of nanoporous atomically thin membranes.

Direct Chemical Vapor Deposition Synthesis of Porous Single-Layer Graphene Membranes with High Gas Permeances and Selectivities.

Single-layer graphene containing molecular-sized in-plane pores is regarded as a promising membrane material for high-performance gas separations due to its atomic thickness and low gas transport resistance. However, typical etching-based pore generation methods cannot decouple pore nucleation and pore growth, resulting in a trade-off between high areal pore density and high selectivity. In contrast, intrinsic pores in graphene formed during chemical vapor deposition are not created by etching. Therefore, intrinsically porous graphene can exhibit high pore density while maintaining its gas selectivity. In this work, the density of intrinsic graphene pores is systematically controlled for the first time, while appropriate pore sizes for gas sieving are precisely maintained. As a result, single-layer graphene membranes with the highest H2 /CH4 separation performances recorded to date (H2 permeance > 4000 GPU and H2 /CH4 selectivity > 2000) are fabricated by manipulating growth temperature, precursor concentration, and non-covalent decoration of the graphene surface. Moreover, it is identified that nanoscale molecular fouling of the graphene surface during gas separation where graphene pores are partially blocked by hydrocarbon contaminants under experimental conditions, controls both selectivity and temperature dependent permeance. Overall, the direct synthesis of porous single-layer graphene exploits its tremendous potential as high-performance gas-sieving membranes.

The Anterior Cruciate Ligament Can Become Hypertrophied in Response to Mechanical Loading: A Magnetic Resonance Imaging Study in Elite Athletes.

BACKGROUND: Evidence, mainly from animal models, suggests that exercise during periods of pubertal growth can produce a hypertrophied anterior cruciate ligament (ACL) and improve its mechanical properties. In humans, the only evidence of ACL hypertrophy comes from a small cross-sectional study of elite weight lifters and control participants; that study had methodological weaknesses and, thus, more evidence is needed. PURPOSE: To investigate bilateral differences in the ACL cross-sectional area (CSA) for evidence of unilateral hypertrophy in athletes who have habitually loaded 1 leg more than the other. STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: We recruited 52 figure skaters and springboard divers (46 female and 6 male; mean age, 20.2 ± 2.7 years) because the former always land/jump on the same leg while the latter always drive the same leg into the board during their hurdle approach. Sport training for all participants began before puberty and continued throughout as well as after. Using oblique axial- and oblique sagittal-plane magnetic resonance imaging, we measured the ACL CSA and the anteroposterior diameter of the patellar tendon, respectively. In addition, isometric and isokinetic knee extensor and flexor peak torques were acquired using a dynamometer. Bilateral differences in the ACL CSA, patellar tendon diameter, and knee muscle strength were evaluated via 2-sided paired-samples t tests. Correlations between the bilateral difference in the ACL CSA and age of training onset as well as between the bilateral difference in the ACL CSA and years of training were also examined. RESULTS: A significantly larger ACL CSA (mean difference, 4.9% ± 14.0%; P = .041), as well as patellar tendon diameter (mean difference, 4.7% ± 9.4%; P = .002), was found in the landing/drive leg than in the contralateral leg. The bilateral difference in the ACL CSA, however, was not associated with the age of training onset or years of training. Last, the isometric knee flexor peak torque was significantly greater in the landing/drive leg than the contralateral leg (mean difference, 14.5% ± 33.8%; P = .019). CONCLUSION: Athletes who habitually loaded 1 leg more than the other before, during, and after puberty exhibited significant unilateral ACL hypertrophy. This study suggests that the ACL may be able to be "trained" in athletes. If done correctly, it could help lower the risk for ACL injuries.

Atomically Precise Control of Carbon Insertion into hBN Monolayer Point Vacancies using a Focused Electron Beam Guide.

Precise controlled filling of point vacancies in hBN with carbon atoms is demonstrated using a focused electron beam method, which guides mobile C atoms into the desired defect site. Optimization of the technique enables the insertion of a single C atom into a selected monovacancy, and preferential defect filling with sub-2 nm accuracy. Increasing the C insertion process leads to thicker 3D C nanodots seeded at the hBN point vacancy site. Other light elements are also observed to bind to hBN vacancies, including O, opening up a wide range of complex defect structures that include B, C, N, and O atoms. The ability to selectively fill point vacancies in hBN with C atoms provides a pathway for creating non-hydrogenated covalently bonded C molecules embedded in the insulating hBN.

Diameter Dependence of Water Filling in Lithographically Segmented Isolated Carbon Nanotubes.

Although the structure and properties of water under conditions of extreme confinement are fundamentally important for a variety of applications, they remain poorly understood, especially for dimensions less than 2 nm. This problem is confounded by the difficulty in controlling surface roughness and dimensionality in fabricated nanochannels, contributing to a dearth of experimental platforms capable of carrying out the necessary precision measurements. In this work, we utilize an experimental platform based on the interior of lithographically segmented, isolated single-walled carbon nanotubes to study water under extreme nanoscale confinement. This platform generates multiple copies of nanotubes with identical chirality, of diameters from 0.8 to 2.5 nm and lengths spanning 6 to 160 µm, that can be studied individually in real time before and after opening, exposure to water, and subsequent water filling. We demonstrate that, under controlled conditions, the diameter-dependent blue shift of the Raman radial breathing mode (RBM) between 1 and 8 cm-1 measures an increase in the interior mechanical modulus associated with liquid water filling, with no response from exterior water exposure. The observed RBM shift with filling demonstrates a non-monotonic trend with diameter, supporting the assignment of a minimum of 1.81 ± 0.09 cm-1 at 0.93 ± 0.08 nm with a nearly linear increase at larger diameters. We find that a simple hard-sphere model of water in the confined nanotube interior describes key features of the diameter-dependent modulus change of the carbon nanotube and supports previous observations in the literature. Longer segments of 160 µm show partial filling from their ends, consistent with pore clogging. These devices provide an opportunity to study fluid behavior under extreme confinement with high precision and repeatability.

Surgery Residents' Experiences With Seriously-Ill and Dying Patients: An Opportunity to Improve Palliative and End-of-Life Care.

OBJECTIVE: To describe how and when surgery residents provided primary palliative care and engaged specialty palliative care services. DESIGN: Phase I consisted of a previously validated survey instrument supplemented with additional questions. We then conducted semistructured interviews with a subset of the survey respondents (Phase II). Using thematic analysis, we characterized surgery residents' perceptions of palliative care delivery among surgical patients. SETTING: General surgery residency programs across the state of Michigan. PARTICIPANTS: General surgery residents across the state of Michigan. All residents in participating programs were invited to complete the survey in Phase I. Phase II consisted of a subset of the survey respondents who underwent semistructured interviews. Interview respondents were sampled to reflect the overall surveyed group. RESULTS: Among 119 survey respondents (response rate 70%), all had encountered a palliative care specialist but only 58.8% had been taught when to consult or to refer to palliative care. Survey respondents reported on a multitude of barriers within the clinician, patient and family, and systemic domains. Interviews expanded on survey findings and 4 influential factors of palliative care delivery emerged: (1) Resident Education and Training; (2) Resident Attitudes Toward Palliative Care; (3) Knowledge of Palliative Care; and (4) Training within a Surgical Culture. CONCLUSIONS: This study reveals how surgery resident training and experiences impact palliative and end-of-life care for surgical patients at teaching institutions. Knowledge of how and when residents are providing primary palliative care and engaging with palliative care services will inform future knowledge and behavioral interventions for trainees who often provide care for patients nearing the end of life.

Enhancing Lithium Insertion with Electrostatic Nanoconfinement in a Lithography Patterned Precision Cell.

The rapidly growing demand for portable electronics, electric vehicles, and grid storage drives the pursuit of high-performance electrical energy storage (EES). A key strategy for improving EES performance is exploiting nanostructured electrodes that present nanoconfined environments of adjacent electrolytes, with the goal to decrease ion diffusion paths and increase active surface areas. However, fundamental gaps persist in understanding the interface-governed electrochemistry in such nanoconfined geometries, in part because of the imprecise and variable dimension control. Here, we report quantification of lithium insertion under nanoconfinement of the electrolyte in a precise lithography-patterned nanofluidic cell. We show a mechanism that enhances ion insertion under nanoconfinement, namely, selective ion accumulation when the confinement length is comparable to the electrical double layer thickness. The nanofabrication approach with uniform and accurate dimensional control provides a versatile model system to explore fundamental mechanisms of nanoscale electrochemistry, which could have an impact on practical energy storage systems.

A nanofluidic ion regulation membrane with aligned cellulose nanofibers.

The advancement of nanofluidic applications will require the identification of materials with high-conductivity nanoscale channels that can be readily obtained at massive scale. Inspired by the transpiration in mesostructured trees, we report a nanofluidic membrane consisting of densely packed cellulose nanofibers directly derived from wood. Numerous nanochannels are produced among an expansive array of one-dimensional cellulose nanofibers. The abundant functional groups of cellulose enable facile tuning of the surface charge density via chemical modification. The nanofiber-nanofiber spacing can also be tuned from ~2 to ~20 nm by structural engineering. The surface-charge-governed ionic transport region shows a high ionic conductivity plateau of ~2 mS cm-1 (up to 10 mM). The nanofluidic membrane also exhibits excellent mechanical flexibility, demonstrating stable performance even when the membrane is folded 150°. Combining the inherent advantages of cellulose, this novel class of membrane offers an environmentally responsible strategy for flexible and printable nanofluidic applications.

Preserved Analgesia With Reduction in Opioids Through the Use of an Acute Pain Protocol in Enhanced Recovery After Surgery for Open Hepatectomy.

BACKGROUND: Enhanced recovery after surgery (ERAS) pathways are designed to restore baseline physiology, mitigate surgical stressors, and hasten recovery. Paramount to this approach is optimal pain control through multimodal analgesia and limiting reliance on opioid-based medications. Recent studies have fostered growing controversy surrounding the use of epidural analgesia in the ERAS setting, especially for higher-risk procedures. We examine the analgesic end points associated with the use of epidural within the ERAS framework for open hepatectomy. METHODS: From November 2013 through March 2016, postoperative analgesic end points including daily morphine equivalent administration and self-reported pain scores were prospectively collected and analyzed for 180 consecutive patients scheduled for open hepatectomy. Patients whose surgeries performed prior to July 2014 were managed using traditional strategy (pre-ERAS, n = 60), and those after July 1 underwent a comprehensive perioperative ERAS pathway (ERAS, n = 120). RESULTS: Patients managed using the ERAS pathway had a significant reduction in morphine equivalent requirements at 24 hours (median, 10.0 vs 116.0 mg; P < 0.001), 48 hours (median, 10.1 vs 85.4 mg; P < 0.001), and 72 hours (median, 2.5 vs 60.0 mg; P < 0.001) compared with pre-ERAS counterparts with a reduction in average pain scores at 24 hours (numeric pain rating scale, 4.1 ± 1.6 vs 5.1 ± 1.8) and similar scores at other time points. Within ERAS, patients who received epidural (n = 87) required significantly less morphine equivalents at 24 hours (median, 2.7 vs 65.0 mg; P < 0.001) and 48 hours (median, 8.0 vs 50.0 mg; P < 0.001) but not at 72 hours (median, 1.3 vs 4.5 mg; P = 0.56), as well as improved pain scores at 24 hours (visual analog scale score, 3.8 ± 1.3 vs 5.0 ± 1.8; P < 0.001) and 48 hours (3.4 ± 1.8 vs 4.7 ± 1.9; P = 0.001) compared with those who did not receive epidural (n = 33). Other associated postoperative end points including provision of fluids, rates of clinically significant hypotension, and lengths of stay between epidural and nonepidural groups were similar. CONCLUSIONS: A novel ERAS protocol for open hepatectomy successfully reduced reliance on perioperative opioids without expensing adequate analgesia compared with traditional care. Patients within ERAS benefitted from application of epidural, which further reduced opioid requirements and optimized pain control without increasing complication rates. Epidurals should remain an integral part of ERAS protocols for liver resection surgery.

Hypertension Risk Subsequent to Gestational Dysglycemia Is Modified by Race/Ethnicity.

Gestational diabetes mellitus is associated with an increased risk of type 2 diabetes mellitus and hypertension. Additionally, gestational dysglycemia has been associated with an increased risk of type 2 diabetes mellitus but not yet associated with hypertension subsequent to pregnancy in long-term follow-up. Therefore, we set out to examine this relationship as well as the role of race/ethnicity in modifying this relationship. We analyzed a prospective observational cohort followed between 1998 and 2007. There were 17 655 women with self-reported race/ethnicity and full-term, live births. A 1-hour 50 g oral glucose-load test and a 3-hour 100 g oral glucose-tolerance test enabled third trimester stratification of women into 1 of 4 glucose-tolerance groups: (1) normal (n=15 056); (2) abnormal glucose-load test (n=1558); (3) abnormal glucose-load and -tolerance tests (n=520); and (4) gestational diabetes mellitus (n=521). Women were then followed for a mean±standard deviation of 4.1±2.9 years after delivery for the development of hypertension. Although gestational diabetes mellitus was associated with an increased risk of hypertension after pregnancy (odds ratio [95% confidence interval]: 1.58 [1.02, 2.45]; P=0.04), dysglycemia defined by an abnormal glucose-load test predicted hypertension only among black women (4.52 [1.24, 16.52]; P=0.02). The risk of hypertension after pregnancy among dysglycemia groups not meeting criteria for gestational diabetes mellitus varied based on the race/ethnicity of the population. Further research on the implications of the intersection of race/ethnicity and gestational dysglycemia on subsequent hypertension is warranted.

Direct Observation of Charge Inversion in Divalent Nanofluidic Devices.

Solid-state nanofluidic devices have proven to be ideal systems for studying the physics of ionic transport at the nanometer length scale. When the geometrical confining size of fluids approaches the ionic Debye screening length, new transport phenomena occur, such as surface mediated transport and permselectivity. Prior work has explored these effects extensively in monovalent systems (e.g., predominantly KCl and NaCl). In this report, we present a new characterization method for the study of divalent ionic transport and have unambiguously observed divalent charge inversion at solid/fluid interfaces. This observation has important implications in applications ranging from biology to energy conversion.

Voltage gated ion and molecule transport in engineered nanochannels: theory, fabrication and applications.

Nanochannels remain at the focus of growing scientific and technological interest. The nanometer scale of the structure allows the discovery of a new range of phenomena that has not been possible in traditional microchannels, among which a direct field effect control over the charges in nanochannels is very attractive for various applications, since it offers a unique opportunity to integrate wet ionics with dry electronics seamlessly. This review will focus on the voltage gated ionic and molecular transport in engineered gated nanochannels. We will present an overview of the transport theory. Fabrication techniques regarding the gated nanostructures will also be discussed. In addition, various applications using the voltage gated nanochannels are outlined, which involves biological and chemical analysis, and energy conversion.

Skeletal muscle metastases: a three-part study of a not-so-rare entity.

OBJECTIVE: Our purposes were to explore the epidemiology of metastases to skeletal muscle and their detection on fused positron emission tomography and computed tomography. MATERIALS AND METHODS: We evaluated the epidemiology of skeletal muscle metastases in the literature and among cases from our hospital and studied the prevalence and appearance of skeletal muscle metastases among 433 patients undergoing fused positron emission tomography and computed tomography for non-small-cell lung cancer. RESULTS: We found 264 cases of skeletal muscle metastases in 151 articles. Mean age was 57.8 years with 67% men. At our hospital we studied 70 cases. Mean patient age was 55.7 years with 63% men. The most common source was lung cancer, and the most common site of involvement was the muscles of the trunk. Among our lung cancer patients undergoing fused positron emission tomography and computed tomography, we found 7 (1.6%) with skeletal muscle metastases. In only one of these seven patients was the metastasis first discovered by another imaging modality. In one patient discovery of the metastasis at fused positron emission tomography and computed tomography changed management. CONCLUSION: Skeletal muscle metastases are not rare. They may be more apparent at fused positron emission tomography and computed tomography than at other staging examinations, particularly contrast-enhanced CT scanning. Radiologists need to be alert to their presence when interpreting staging examinations in cancer patients.