5,827 research outputs found

    Space-charge-limited flows in the quantum regime

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    This paper reviews the recent developments of space-charge-limited (SCL) flow or Child-Langmuir (CL) law in the quantum regime. According to the classical CL law for planar diodes, the current density scales as 3/23∕2’s power of gap voltage and to the inverse squared power of gap spacing. When the electron de Broglie wavelength is comparable or larger than the gap spacing, the classical SCL current density is enhanced by a large factor due to electron tunneling and exchange-correlation effects, and there is a new quantum scaling for the current density, which is proportional to the 1/21∕2’s power of gap voltage, and to the inverse fourth-power of gap spacing. It is also found that the classical concepts of the SCL flow such as bipolar flow, transit time, beam-loaded capacitance, emitted charge density, and magnetic insulation are no longer valid in quantum regime. In the quantum regime, there exists a minimum transit time of the SCL flows, in contrast to the classical solution. By including the surface properties of the emitting surface, there is a threshold voltage that is required to obtain the quantum CL law. The implications of the Fowler-Nordheim-like field emission in the presence of intense space charge over the nanometer scale is discussed.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87757/2/056701_1.pd

    Fermented pumpkin-based beverage inhibits key enzymes of carbohydrate digesting and extenuates postprandial hyperglycemia in type-2 diabetic rats

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    A novel functional pumpkin-based beverage fermented by Lactobacillus mali K8 (FPJ) was produced. FPJ possessed higher ferric reducing antioxidant power (FRAP, 270.76 μM TE/100 ml) and radical scavenging activity (RSA‒IC50, 7.56 mg ml‒1) compared with non-inoculated control (PJ) (102.99 μM TE/100 ml and IC50 52.78 mg ml‒1). Up to an IC50 of 23.71 and 5.27 mg ml‒1 of α-amylase and α-glucosidase inhibitions were demonstrated by FPJ, close to that of acarbose (IC50 4.86 and 0.048 mg ml‒1, respectively). Oral administration of FPJ significantly lowered post-meal blood glucose levels in low-dose streptozotocin (STZ) and high-fat diet-treated rat – a reduction of incremental areas under the curve 2334 versus 2689 mmol min l‒1. Thus, it may open new dietary measure in managing postprandial hyperglycaemia

    Preliminary results of fast neutron treatments in carcinoma of the pancreas

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    A group of 30 patients with adenocarcinoma of the pancreas including some patients with very advanced disease, were treated with the so-called mixed beam modality employing photon treatments three times per week and neutron treatments twice a week. Two hundred Rads or equivalent Rads (RBE 3.3) were given in daily fractions aiming at a total dose of 6000 Rads in 6 to 8 weeks. The treatments were well tolerated and significant palliation was achieved in 26 to 30 cases. Twelve months survival was 33 percent with a median survival of 7 months or 210 days. Treatment techniques and localization procedures are discussed

    Fermi surface and quasiparticle dynamics of Na(x)CoO2 {x=0.7} investigated by Angle-Resolved Photoemission Spectroscopy

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    We present an angle-resolved photoemission study of Na0.7CoO2, the host cobaltate of the NaxCoO2.yH2O series. Our results show a large hexagonal-like hole-type Fermi surface, an extremely narrow strongly renormalized quasiparticle band and a small Fermi velocity. Along the Gamma to M high symmetry line, the quasiparticle band crosses the Fermi level from M toward Gamma consistent with a negative sign of effective single-particle hopping (t ): t is estimated to be about 8 meV which is on the order of exchange coupling J in this system. This suggests that t ~ J ~ 10 meV is an important energy scale in the system. Quasiparticles are well defined only in the T-linear resistivity regime. Small single particle hopping and unconventional quasiparticle dynamics may have implications for understanding the unusual behavior of this new class of compounds.Comment: Revised text, Added Figs, Submitted to PR

    Assessing synthetic milk through the detection of anionic detergents in milk: a concise review

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    The emergence of synthetic milk as a deceptive method for economic gains involves the incorporation of adulterants such as starch, urea, inexpensive vegetable oils, glucose detergent, water, and preservatives. This fraudulent mixture, seamlessly integrated with pure milk, deceives consumers by maintaining a natural taste and appearance. However, this unethical practice poses significant health risks, particularly to vulnerable demographics like children, pregnant women, and individuals with compromised immune systems. Despite being prevalent in both developed and developing countries, this deceptive practice could extend to other regions, given the global demand for milk and dairy products. Various methods exist for detecting synthetic milk, and one prominent approach involves identifying anionic detergent, which serves as a key component in the production of synthetic milk, acting as an emulsifier for vegetable oils and other ingredients. Therefore, this paper aims to provide an in-depth review of the role of detergent in synthetic milk production, highlighting the evolution of detection technologies. Additionally, a comparative analysis of the strengths and limitations of the method for identifying anionic detergent in synthetic milk is presented

    Influence of operating parameters on the biodegradation of steroid estrogens and nonylphenolic compounds during biological wastewater treatment processes

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    This document is the unedited author's version of a Submitted Work that was subsequently accepted for publication in Environmental Science & Technology, copyright © American Chemical Society after peer review. To access the final edited and published work see http://pubs.acs.org/doi/abs/10.1021/es901612v.This study investigated operational factors influencing the removal of steroid estrogens and nonylphenolic compounds in two sewage treatment works, one a nitrifying/denitrifying activated sludge plant and the other a nitrifying/denitrifying activated sludge plant with phosphorus removal. Removal efficiencies of >90% for steroid estrogens and for longer chain nonylphenol ethoxylates (NP4−12EO) were observed at both works, which had equal sludge ages of 13 days. However, the biological activity in terms of milligrams of estrogen removed per day per tonne of biomass was found to be 50−60% more efficient in the nitrifying/denitrifying activated sludge works compared to the works which additionally incorporated phosphorus removal. A temperature reduction of 6 °C had no impact on the removal of free estrogens, but removal of the conjugated estrone-3-sulfate was reduced by 20%. The apparent biomass sorption (LogKp) values were greater in the nitrifying/denitrifying works than those in the nitrifying/denitrifying works with phosphorus removal for both steroid estrogens and nonylphenolic compounds possibly indicating a different cell surface structure and therefore microbial population. The difference in biological activity (mg tonne−1 d−1) identified in this study, of up to seven times, suggests that there is the potential for enhancing the removal of estrogens and nonylphenols if more detailed knowledge of the factors responsible for these differences can be identified and maximized, thus potentially improving the quality of receiving waters.Public Utilities Board (Singapore), Anglian Water Ltd, Severn Trent Water Ltd, Thames Water Utilities Ltd, United Utilities 393 Plc and Yorkshire Water Services
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