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Developing simpler, more accessible, and more affordable methods for the determination of the boiling point of microscale amounts of liquid may lead to increased utilization in research and teaching laboratories as an analytical technique. Our efforts toward that goal have revealed that digital hot plates can be used as the heat source. One option is to simply use a test tube and a digital thermometer, requiring 300 µL of liquid that accurately determines boiling points that range from 35 to 150 °C. An alternative method, requiring as little as 30 µL of liquid, utilizes a modified aluminum block and a temperature control probe coupled to the digital hot plate that results in the accurate determination of boiling points that range from 35 to 205 °C. Both modifications to the Siwoloboff-Wiegand method provide consistent, reliable, and accurate boiling points for a variety of liquids with a wide range of boiling points.

We report thermal to electrical energy conversion from a 150nm thick BaTiO3 film using pyroelectric cycles at 1kHz. A microfabricated platform enables temperature and electric field control with temporal resolution near 1μs. The rapid electric field changes as high as 11×105kV/cm-s, and temperature change rates as high as 6×105K/s allow exploration of pyroelectric cycles in a previously unexplored operating regime. We investigated the effect of phase difference between electric field and temperature cycles, and electric field and temperature change rates on the electrical energy generated from thermal-electrical cycles based on the pyroelectric Ericsson cycle. Complete thermodynamic cycles are possible up to the highest cycle rates tested here, and the energy density varies significantly with phase shifts between temperature and electric field waveforms. This work could facilitate the design and operation of pyroelectric cycles at high cycle rates, and aid in the design of new pyroelectric systems.

Positive vertical margins (VMs) are common after endoscopic submucosal dissection (ESD) of T1b esophageal cancer (EC) and are associated with an increased risk of recurrence. Traction during ESD provides better exposure of the submucosa and may allow deeper dissection, potentially reducing the risk of positive VMs. We conducted a retrospective multicenter study to compare the proportion of resections with positive VMs in ESD performed with versus without traction in pathologically staged T1b EC. Patients who underwent ESD revealing T1b EC (squamous or adenocarcinoma) at 10 academic tertiary referral centers in the United States (n = 9) and Brazil (n = 1) were included. Demographic and clinical data were abstracted. ESD using either traction techniques (tunneling, pocket) or traction devices (clip line, traction wire) were classified as ESD with traction (Tr-ESD) and those without were classified as conventional ESD without traction. The primary outcome was a negative VM. Multivariable logistic regression was used to assess associations with negative VMs. A total of 166 patients with pathologically staged T1b EC underwent Tr-ESD (n = 63; 38%) or conventional ESD without traction (n = 103; 62%). Baseline factors were comparable between both groups. On multivariable analysis, Tr-ESD was found to be independently associated with negative VMs (odds ratio, 2.25; 95% confidence interval, 1.06-4.91; P =.037) and R0 resection (odds ratio, 2.83; 95% confidence interval, 1.33-6.23; P =.008). Tr-ESD seems to be associated with higher odds of negative VMs than ESD without traction for pathologically staged T1b EC, and future well-conducted prospective studies are warranted to establish the findings of the current study. [Display omitted] [ABSTRACT FROM AUTHOR]

To accommodate societal electrification and decarbonization, renewable energy resources continue to expand their share of the global energy market. The intermittency of renewable energy technologies as well as the high power density of modern electrified platforms necessitates the need for both efficient thermal management and high-density thermal storage. Phase change materials are a promising passive thermal energy storage solution. However, difficulties with efficient system implementation stemming from the inherent melt pool formation hinder their potential. We develop an innovative strategy, termed dynamic phase change material "dynPCM," to address this thermal transport issue by ensuring a constant, thin, melt layer. We analyze the fundamental limits of dynPCMs, characterize the peak achievable heat flux and energy/power densities, estimate the power consumption of dynPCM systems, and investigate the fundamental physics which govern dynPCM behavior. We show that dynPCM can eliminate the classical trade-off seen between energy density and power density and achieve ultrahigh heat fluxes, ∼105 W/cm2, with heat flux-to-required power ratios as high as ∼107. We also demonstrate achievable power densities as high as ∼100 W/cm3 at energy densities as high as ∼10 kJ/cm3. Throughout this work, we develop a methodology to evaluate the operating limits, enabling adaptation of the dynPCM system concept to a variety of applications and industries. [ABSTRACT FROM AUTHOR]

We report pyroelectric emission from PbZrxTi1-xO 3 (PZT) thin films on nanometer-sharp tips. The epitaxial PZT films are 30 nm thick and grown directly on single-crystal silicon tips. Pyroelectric emission occurs for heating rates of 50 °C/min in a 20 V/μm external field. The emission current is a maximum of 240 nA when the heating rate is 100 °C/min and the electric field strength is 6.7 V/μm. The emitted charge is ∼7 of that expected for a perfect thin film emitter of epitaxial PbZr xTi1-xO3. We calculate that pyroelectric emission can occur without an applied field if the heating rate exceeds 4.0 × 107 °C/min. © 2013 AIP Publishing LLC.

The authors report field emission from nanometer-sharp tips of polarized PbZrxTi1-xO3 (PZT), silicon, and platinum. The PZT nanoemitters are fabricated in a batch fabrication process from single-crystal silicon tips that are coated with a 30 nm thick film of crystalline PZT. The nanoemitters start to emit electrons at fields as low as 2 V/μm and reach threshold emission, or turn-on, at fields as low as 3.9 V/μm. The turn-on field is 3.9 V/μm for PbZr0.2Ti 0.8O3, 6.8 V/μm for PbZr0.52Ti 0.48O3, and 10.75 V/μm for PbZr0.8Ti 0.2O3. The silicon nanoemitters have an electron emission turn-on field of 7.2 V/μm, and the platinum nanoemitters have an electron emission turn-on field of 5.75 V/μm. Using a Fowler-Nordheim analysis, the calculated effective work function of the PbZr0.2Ti 0.8O3 film is 1.00 eV, and the field amplification factor is ∼1526. © 2013 American Vacuum Society.

Recent Western studies support the safety and efficacy of endoscopic submucosal dissection (ESD) for lesions throughout the GI tract. Although admission for observation after ESD is standard in Asia, a more selective approach may optimize resource utilization. We aimed to evaluate the safety and feasibility of same-day discharge (SDD) after ESD and factors associated with admission. This was a post hoc analysis of a multicenter, prospective cohort of patients undergoing ESD (2016-2021). The primary end points were safety of SDD and factors associated with post-ESD admission. Of 831 patients (median age, 67 years; 57% male) undergoing 831 ESDs (240 performed in the esophagus, 126 in the stomach, and 465 in the colorectum; median lesion size, 44 mm), 588 (71%) were SDD versus 243 (29%) admissions. Delayed bleeding and perforation occurred in 12 (2%) and 4 (.7%) of SDD patients, respectively; only 1 (.2%) required surgery. Of the 243 admissions, 223 (92%) were discharged after ≤24 hours of observation. Interestingly, larger lesion size (>44 mm) was not associated with higher admission rate (odds ratio [OR],.5; 95% confidence interval [CI],.3-.8; P =.001). Lesions in the upper GI tract versus colon (OR, 1.7; 95% CI, 1.1-2.6; P =.01), invasive cancer (OR, 1.9; 95% CI, 1.2-3.1; P =.01), and adverse events (OR, 2.7; 95% CI, 1.5-4.8; P =.001) were independent factors for admission. Admissions were more likely performed by endoscopists with ESD volume <50 cases (OR, 2.1; 95% CI, 1.3-3.3; P =.001) with procedure time >75 minutes (OR, 13.5; 95% CI, 8.5-21.3; P <.0001). SDD after ESD can be safe and feasible. Patients with invasive cancer, lesions in the upper GI tract, longer procedure times, or procedures performed by low-volume ESD endoscopists are more likely to be admitted postprocedure. Risk stratification of patients for SDD after ESD should help optimize resource utilization and enhance ESD uptake in the West. (Clinical trial registration number: NCT02989818.) [ABSTRACT FROM AUTHOR]

This article examines how a faculty member's status--either tenured or tenure-track--might affect the grades assigned to students in a writing class. We begin with a brief review of the research surrounding faculty to student assessment practices and follow with specific controversies regarding faculty motivation pertaining to grading practices. We interpret the grade distributions of tenured and tenure-track faculty members teaching a sophomore-level writing course in an English Department at a small, public liberal arts university in Virginia, examine the relationship between grade distributions and faculty rank, and conclude that tenure-track faculty grade more leniently than their tenured colleagues, primarily in the number of "A" grades assigned. The results of this study suggest that tenured professors tend to award fewer "As" than tenure-track professors. We posit that at universities where emphasis is placed upon teaching, two specific patterns emerge: reciprocity may be an unspoken agreement between some faculty and students with regard to the exchange of good grades for good evaluations, or with experience comes rigor. (Contains 1 figure and 1 table.)