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Chip-scale gas chromatography:From injection through detection

Microsystems & Nanoengineering 2015年第1期1卷 8-15页

作者： Muhammad Akbar Michael Restaino Masoud Agah vt mems laboratory Bradley Department of Electrical and Computer EngineeringVirginia TechBlacksburgVA 24061USA Department of Biomedical Engineering and Mechanics Virginia TechBlacksburgVA 24061USA

Miniaturized gas chromatography(μGC)systems hold potential for the rapid analysis of volatile organic compounds(VOCs)in an extremely compact and low-power enabled ***,we utilize microfabrication technology to demonstrate the single chip integration of the key components of aμGC system in a two-step planar fabrication *** 1.5×3 cm microfluidic platform includes a sample injection unit,a micromachined semi-packed separation column(μSC)and a micro-helium discharge photoionization detector(μDPID).The sample injection unit consists of a T-shaped channel operated with an equally simple setup involving a single three-way fluidic valve,a micropump for sample loading and a carrier gas supply for subsequent analysis of the *** innovative sample injection technique described herein requires a loading time of only a few seconds and produces sharp and repeatable sample pulses(full width at half maximum of approximately 200 ms)at a carrier gas flow rate that is compatible with efficient chromatographic ***,our comprehensive characterization of the chip reveals that a wide variety of VOCs with boiling points in the range of 110–216℃ can be analyzed in less than 1 min by optimizing the flow and temperature programming ***,the analysis of four VOCs at the concentration level of one part per million in an aqueous sample(which corresponds to a headspace concentration in the lower parts-per-billion regime)was performed with a sampling time of only 6 *** μDPID has demonstrated a linear dynamic range over three orders of *** system presented here could potentially be used to monitor hazardous VOCs in real time in industrial workplaces and residential settings.

关键词： gas chromatography lab-on-a-chip mems microsystem

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Ultrasound Attenuation in Biological Tissue Predicted by the Modified Doublet Mechanics Model

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Chinese Physics Letters 2009年第7期26卷 188-191页

作者：江鑫刘晓宙吴君汝 Key laboratory of Modern Acoustics Institute of Acoustics Nanjing University Nanjing 210093 Department of Physics University of Vermont Burlington VT 05405 USA

Experimental results have shown that in the megahertz frequency range the relationship between the acoustic attenuation coefficient in soft tissues and frequency is nearly linear. The classical continuum mechanics （CCM）, which assumes that the materiaJ is uniform and continuous, faJls to explain this relationship particularly in the high megahertz range. Doublet mechanics （DM） is a new elastic theory which takes the discrete nature of material into account. The current DM theory however does not consider the loss. We revise the doublet mechanics （DM） theory by including the loss term, and cMculate the attenuation of a soft tissue as a function of frequency using the modified the DM theory （MDM）. The MDM can now well explain the nearly linear relationship between the acoustic attenuation coefficient in soft tissues and frequency.

关键词： sea surface nonliear interaction numerical method

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Growth trends and environmental drivers of major tree species of the northern hardwood forest of eastern North America

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Journal of Forestry Research 2023年第1期34卷 37-50页

作者： Rebecca L.Stern Paul G.Schaberg Shelly A.Rayback Christopher F.Hansen Paula F.Murakami Gary J.Hawley Rubenstein School of Environment and Natural Resources The University of VermontBurlingtonVT 05405USA ERM MalvernPA 19355USA Forest Service United States Department of AgricultureNorthern Research StationBurlingtonVT 05405USA Department of Geography The University of VermontBurlingtonVT 05405USA

The future health and productivity of tree species in the northern hardwood forest of eastern North America are uncertain considering changes in climate and pollution loading *** better understand the trajectory of the northern hardwood forest,we studied the growth of three tree species emblematic of it:sugar maple(Acer saccharum Marsh),American beech(Fagus grandifolia Ehrh.),and yellow birch(Betula alleghaniensis Britton),plus a fourth species,red maple(Acer rubrum L.),whose abundance has increased in the *** also analyzed the link between growth and several factors for690 trees in 45 plots throughout Vermont,USA:tree age and size,site elevation,and climate and acid deposition *** their chronologies(1945-2014),all four species exhibited increasing growth followed by plateaued growth indicative of a maturing *** all species,summer moisture was positively correlated with growth,summer temperature was negatively associated with growth,and winter moisture or snow were positively correlated with *** last association was expected for sugar ***,our data suggest that winter snowpack may be more broadly relevant in sustaining tree growth in a region where snow has historically insulated the soil from freezing that can damage roots and lead to reduced aboveground *** of pollution deposition were also correlated with growth for all species except American beech—a species with documented tolerance to pollutant *** the four species studied,red maple had the fewest associations with environmental variables,which suggests that it may be less susceptible to growth reductions as the climate changes.

关键词： Climate change Sugar maple Yellow birch American beech Red maple

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Reactive oxygen species in the progression and treatment of malignant mesothelioma

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Journal of Cancer Metastasis and Treatment 2022年第1期8卷 210-220页

作者： Ava Cote Terri Messier Brian Cunniff Department of Pathology and laboratory Medicine Redox Biology ProgramUniversity of Vermont Larner College of MedicineBurlingtonVT 05405USA University of Vermont Cancer Center University of Vermont Larner College of MedicineBurlingtonVT 05405USA

Malignant mesothelioma(MM)is an aggressive cancer that affects the pleural and peritoneal mesothelial lining of the lungs and *** rates for patients with MM remain extremely low and effective treatments are *** tumors harbor both genotypic and phenotypic features that indicate MM tumor cells are under increased oxidative stress,similar to other aggressive *** increased oxidative stress in MM cells supports aggressive growth while providing a therapeutic vulnerability exploitable by redox-modulating *** tumor cells also exhibit altered mitochondrial structure and function that contribute to the disease through perturbations in metabolism and reactive oxygen species(ROS)production and *** the altered redox status in cancer through increasing cellular ROS levels directly or inhibiting cellular antioxidant pathways and disrupting ROS scavenging mechanisms has become an exciting area for therapeutic *** review discusses ROS sources and signaling,mitochondrial structure and function and targeting mitochondria ROS as a therapeutic approach for the treatment of MM.

关键词： Malignant mesothelioma targeting cellular redox status pro-oxidant therapy

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Hospitalization for variceal hemorrhage in an era with more prevalent cirrhosis

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World Journal of Gastroenterology 2014年第32期20卷 11326-11332页

作者： Nicholas Lim Michael J Desarno Steven D Lidofsky Eric Ganguly Division of Gastroenterology and Hepatology University of Vermont College of Medicine Burlington VT 05401 United States Department of Biostatistics University of Vermont College of Medicine Burlington VT 05401 United States

AIM: To examine hospitalization rates for variceal hemorrhage and relation to cause of cirrhosis during an era of increased cirrhosis prevalence.

关键词： Varices Gastrointestinal bleeding Cirrhosis Hospitalization Portal hypertension

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Hepatoxicity associated with weight-loss supplements: A case for better post-marketing surveillance

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World Journal of Gastroenterology 2009年第14期15卷 1786-1787页

作者： Ano Lobb Public Health Consultant 80 Lepage Rd Barre VT 05641 United States

There is a growing number of case reports of hepatoxicity from the widely marketed weight-loss supplement Hydroxycut, which contains the botanical ingredient Garcinia cambogia . These case reports may substantially undercount the true magnitude of harm. Based on the past experience with harmful dietary supplements, US regulators should assume the more precautionary approach favored by Canada and Europe. Lacking effective adverse event surveillance for supplements, or the requirements to prove safety prior to coming to the market, case reports such as those summarized here assume added importance.

关键词： Hydroxycut Dietary supplements Garciniacambogia Liver failure Weight loss Super citrimax Hca-sx

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Review of pharmacological inhibition of thyroid cancer metabolism

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Journal of Cancer Metastasis and Treatment 2021年第1期7卷 640-658页

作者： Cole D.Davidson Frances E.Carr Department of Pharmacology Larner College of MedicineBurlingtonVT 05405USA University of Vermont Cancer Center BurlingtonVT 05405USA

Thyroid cancer(TC)is the most common malignancy of the endocrine system and has been rapidly increasing in incidence over the past few *** TCs metastasize quickly and often levy poor prognoses,as they are frequently resistant to first-line treatment *** diagnosed with aggressive,dedifferentiated TC have a prognosis of under a year with the most current treatment *** many cancers,TCs also exhibit altered cell metabolism,which enhances the cell’s ability to generate energy,protect against reactive oxygen species,and synthesize macromolecules such as lipids,proteins,and nucleotides for *** and enzyme profiling of TC tissues and cell lines have uncovered several dysregulated metabolic pathways such as glycolysis,the pentose phosphate pathway,glutamine metabolism,and pyrimidine *** aberrations are most often due to overexpression of rate-limiting enzymes or metabolite *** pathways pose attractive therapeutic targets in aggressive TC and may serve to work in tandem with standard therapeutics such as kinase inhibitors depending on the genetic,metabolic,and signaling backgrounds of individual *** studies are needed to clearly delineate altered metabolic targets across TC subtypes for implementing therapeutic metabolic inhibitors that have shown success in other aggressive tumors.

关键词： Thyroid cancer tumor metabolism metabolic inhibitors Warburg effect cell signaling

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The Oligopeptide Transporters： A Small Gene Family with a Diverse Group of Substrates and Functions？

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Molecular Plant 2011年第3期4卷 407-415页

作者： Mark Lubkowit Department of Biology Saint Michael's College 1 Winooski Park Colchester VT 05439 USA

Genes in the Oligopeptide Transport family encode integral membrane proteins that are believed to trans- locate their substrates from either the extracellular environment or an organelle into the cytosol. Phylogenetic analyses of plant transporters have revealed two distant clades. the Yellow Stripe-Like （YSL） proteins and the so-called Oligopeptide Transporters （OPTs）, for which the family was named. Three categories of substrates have been identified for this family： small peptides, secondary amino acids bound to metals, and glutathione. Notably, the YSL transporters are involved in metal homeostasis through the translocation of metal-chelates, indicating a level of conservation both in biological func- tion as well as substrates. In contrast, the functions of OPT proteins seem to be less defined and, in this review, I will examine the supporting and contradictory evidence for the proposed roles of OPTs in such diverse functions as long-dis- tance sulfur distribution, nitrogen mobilization, metal homeostasis, and heavy metal sequestration through the transport of glutathione, metal-chelates, and peptides.

关键词： Molecular transport nutrient and metal transport transporters Oligopeptide Transporters.

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Numerical and analytical investigations for the SOI LDMOS with alternated high-k dielectric and step doped silicon pillars

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Chinese Physics B 2020年第3期29卷 460-467页

作者： Jia-Fei Yao Yu-Feng Guo Zhen-Yu Zhang Ke-Meng Yang Mao-Lin Zhang Tian Xia College of Electronic and Optical Engineering&College of Microelectronics Nanjing University of Posts and TelecommunicationsNanjing 210023China National and Local Joint Engineering laboratory of RF Integration and Micro-Assembly Technology Nanjing 210023China School of Electrical Engineering University of VermontBurlingtonVT 05405USA

This paper presents a new silicon-on-insulator(SOI) lateral-double-diffused metal-oxide-semiconductor transistor(LDMOST) device with alternated high-k dielectric and step doped silicon pillars(HKSD device). Due to the modulation of step doping technology and high-k dielectric on the electric field and doped profile of each zone, the HKSD device shows a greater performance. The analytical models of the potential, electric field, optimal breakdown voltage, and optimal doped profile are derived. The analytical results and the simulated results are basically consistent, which confirms the proposed model suitable for the HKSD device. The potential and electric field modulation mechanism are investigated based on the simulation and analytical models. Furthermore, the influence of the parameters on the breakdown voltage(BV) and specific on-resistance(R_(on,sp)) are obtained. The results indicate that the HKSD device has a higher BV and lower R_(on,sp) compared to the SD device and HK device.

关键词： high-k dielectric step doped silicon pillar model breakdown voltage

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Reliability of a simple fluoroscopic image to assess leg length discrepancy during direct anterior approach total hip arthroplasty

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World Journal of Orthopedics 2021年第11期12卷 850-858页

作者： Sandi Caus Hailee Reist Christopher Bernard Michael Blankstein Nathaniel J Nelms The Robert Larner College of Medicine University of VermontBurlingtonVT 05405United States Department of Orthopaedics and Rehabilitation Unviversity of VermontBurlingtonVT 05405United States

BACKGROUND Direct anterior approach(DAA)total hip arthroplasty(THA)in a supine position provides a unique opportunity to assess leg length discrepancy(LLD)intraoperatively with *** fluoroscopic techniques are useful but are generally complicated or *** the use of multiple techniques for leg length assessment,LLD continues to be a major post-operative source of patient dissatisfaction further emphasizing the importance of near-anatomic *** utility of an alternative direct measurement of LLD on an intra-operative fluoroscopic pelvic image during DAA THA has not been *** To determine the reliability of a novel simple intra-operative measurement of LLD using a parallel line technique on a single fluoroscopic digital image of the *** One hundred and seventy-one patients who underwent DAA THA were included for ***-operative fluoroscopic and post-operative anterior-posterior radiographs were imported to TraumaCad and calibrated for LLD *** was measured on each image using the right-left hip differences in lesser trochanter to pelvic reference line *** reference points included the teardrops and *** LLD was compared to the gold-standard measurement of LLD measured on a post-operative *** Mean absolute difference in teardrop referenced LLD between fluoroscopic and post-operative radiographs was 2.17 mm and based on the ischia mean absolute difference was 2.63 *** regression of fluoroscopic and post-operative radiograph LLD based on teardrop and ischia LLD found r2 values of 0.57 and 0.84,*** absolute difference between fluoroscopic and postoperative x-ray LLD was within 5 mm in 95%of cases regardless of pelvic *** This study demonstrates that a single fluoroscopic view obtained during DAA THA for leg length assessment is clinically useful.

关键词： Leg-length discrepancy Total hip arthroplasty Intra-operative fluoroscopy Direct anterior approach Limb asymmetry

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