非侵入式脉搏血氧检测系统设计

氧气是新陈代谢的基础,血氧饱和度作为一项重要的健康指标,在临床医学以及家庭保健等方面有着广泛的应用前景。本文以TI的超低功耗的MSP430微处理器作为系统的核心,设计了一款基于数字血氧探头的脉搏血氧检测系统,并实现了基于VC的下位机与上位机的串行通信。数字信号处理方案简化了电路设计,实验结果证实本方案能够有效降低成本、减少开发板的面积,从而更好的满足市场需求。     

Study and Evaluation of Aging Performance of Petroleum Asphalts and Their Constituents During Oxygen Absorption. I. Oxygen Absorption Behaviors and Kinetics

Abstract

The oxygen absorption behaviors and kinetics of Shanjiasi, Shengli, and Renqiu petroleum asphalts and their constituents including saturates, aromatics, resins, and asphaltenes were successfully studied at 50°C, 0.133 MPa (O₂) and 1 mm sample film in darkness by means of precise measurement of oxygen pressure changes in reactor. The experimental results that the resin and the asphaltene can easily absorb oxygen and they are more active constituents in petroleum asphalt, while the saturate hardly absorbs oxygen, which is the most stable constituent of petroleum asphalt. The better the antiaging performance of straight run petroleum asphalt, the more stable its constituents and the less oxygen they absorb generally. The oxygen absorption rate of asphaltene diluted with the lower viscous saturate is obviously higher than that of pure asphaltene. The resin constituent of Shanjiasi asphalt could remarkably improve the antiaging ability of Shengli asphalt by the constituent substitution. The kinetic model of maximum combined oxygen presented in this paper could satisfactorily explain the oxygen absorption behaviors of petroleum asphalts and their constituents, and the oxygen absorption quantities calculated by the model are very identified with the test ones.     

Study and Evaluation of Aging Performance of Petroleum Asphalts and Their Constituents During Oxygen Absorption. II. Chemical Group Composition and Structure Changes

Abstract

The changes of the chemical group compositions and the structures of Chinese Shanjiasi, Shengli, and Renqiu petroleum asphalts and their constituents during oxygen absorption were successfully studied based on the sample oxygen absorption behaviors. The research results show that every asphalt constituent after absorbing oxygen would change into the near heavier one with the exception of saturates, of which the greatest is the conversion rate of resin into asphaltene. The oxygen molecules absorbed by samples are mainly converted into the oxygen atoms in some oxygen-containing function groups, such as O-H, C=O, and S=O groups. The asphalt colloidal stabilities deteriorate clearly and the molecular weight distributions of asphalts and their constituents spread toward higher molecular weights. The molecular weights of all samples increase gradually after oxygen absorption. Resins and asphaltenes are the more unstable constituents in asphalts as shown by their evident changes after oxygen absorption. The changes of Shengli asphalt and its constituents absorbing more easily oxygen are clearly greater than those of Shanjiasi asphalt and its constituents.     

Shelf life of case-ready beef steaks (Semitendinosus muscle) stored in oxygen-depleted master bag system with oxygen scavengers and CO2/N2 modified atmosphere packaging

This study aims to evaluate the stability of beef from Semitendinosus muscle packaged in oxygen permeable wrapped-tray units and stored in a master bag system, with and without oxygen scavengers. Changes in the atmosphere composition, microbiological indexes, myoglobin forms and color parameters were monitored during the storage in master bag, blooming and display life. The presence of scavengers reduced rapidly the oxygen concentration and maintained it at values not detectable instrumentally. Within few days of storage in master bags, the resolution of the transient discoloration was completed and the meat quality was maintained over the anoxic storage. After the removal from master bags meat bloomed completely reaching OxyMb level and Chroma values higher than those on fresh meat at t₀. During 48 h of display life at 4 °C, quality attributes had a decay slower than samples stored traditionally in air. Without scavengers the oxygen caused the irreversible discoloration within 7 days, due to the formation of metmyoglobin on the surface.     

炉顶MN管导烟车的应用效果

引进了炉顶MN管导烟车及机侧炉门密封装置,利用高压氨水的高速喷射在桥管内形成局部负压,使装煤产生的荒煤气在负压作用下抽入集气管,进行回收利用,解决了炉头和炉顶烟气外逸的问题,具有较好的环保和经济效益。     

Resistive switching memory characteristics of Ge/GeOx nanowires and evidence of oxygen ion migration

The resistive switching memory of Ge nanowires (NWs) in an IrO_x/Al₂O₃/Ge NWs/SiO₂/p-Si structure is investigated. Ge NWs with an average diameter of approximately 100 nm are grown by the vapor–liquid-solid technique. The core-shell structure of the Ge/GeO_x NWs is confirmed by both scanning electron microscopy and high-resolution transmission electron microscopy. Defects in the Ge/GeO_x NWs are observed by X-ray photoelectron spectroscopy. Broad photoluminescence spectra from 10 to 300 K are observed because of defects in the Ge/GeO_x NWs, which are also useful for nanoscale resistive switching memory. The resistive switching mechanism in an IrO_x/GeO_x/W structure involves migration of oxygen ions under external bias, which is also confirmed by real-time observation of the surface of the device. The porous IrO_x top electrode readily allows the evolved O₂ gas to escape from the device. The annealed device has a low operating voltage (<4 V), low RESET current (approximately 22 μA), large resistance ratio (>10³), long pulse read endurance of >10⁵ cycles, and good data retention of >10⁴ s. Its performance is better than that of the as-deposited device because the GeO_x film in the annealed device contains more oxygen vacancies. Under SET operation, Ge/GeO_x nanofilaments (or NWs) form in the GeO_x film. The diameter of the conducting nanofilament is approximately 40 nm, which is calculated using a new method.     

高温氧气用金属硬密封球阀的研究与设计

介绍了高温氧气用金属硬密封球阀的原理与结构特点,阐述了其设计重点和生产控制过程。     

Self-assembled nano-phase particles for enhanced oxygen barrier coatings on polymeric materials

Aqueous-based inorganic–organic hybrid coating materials comprising self-assembled nanophase particles (SNAP) were investigated for their potential to confer high gas barrier performance to flexible polymeric substrates, particularly to improve suitability of the substrates as encapsulation materials for organic photovoltaic (OPV) devices. Potential benefits of this approach include versatility in barrier coating formulation to achieve specific barrier properties, and application of coatings in a reel-to-reel process under ambient conditions. The present study focused on enhancement of the oxygen barrier performance of polypropylene (PP) substrates by applying SNAP-based coatings with and without the addition of an oxygen scavenging additive. SNAP particles were characterised using ²⁹Si NMR and dynamic light scattering, and coatings were analysed using atomic force microscopy and X-ray photoelectron spectroscopy. SNAP particle preparation and coating formulation was optimised with respect to oxygen transmission rate (OTR) of the coating on PP, and mechanical properties of the coating solution. In the absence of oxygen scavenger, the lowest OTR attained for the SNAP-based coatings was 0.87 cm³ mil m⁻² day⁻¹ atm⁻¹. The OTR was further reduced to 0.22 cm³ mil m⁻² day⁻¹ atm⁻¹ on addition of 9,10-anthraquinone-2,6-dissulfonic acid (AQDS) into the coating as an oxygen scavenger. These results represent a decrease in OTR by 4 orders of magnitude compared with uncoated PP, and the oxygen barrier obtained by addition of AQDS surpasses the performance of many plastic materials considered to be high oxygen barriers in the food and pharmaceutical industries.     

MICROBUBBLES FOR ENHANCEMENT OF OXYGEN TRANSFER IN XANTHAN GUM FERMENTATION

This study investigates the use of microbubble sparging for enhancing oxygen transfer and product yield during xanthan gum fermentation. Fermentation runs with full air sparging and partially substituted microbubble sparging were compared for the parameters biomass, xanthan, oxygen uptake, and energy levels. Microorganisms were found compatible at numerous Tween-20 levels and further showed considerable resistance to shear conditions in the microbubble generator. Microbubbles with a size of about 145 μm, gas hold up of 65%, and foam stability of about 3 min. resulted at standardized microbubble generator operating conditions (8000 rpm, 2 min., 300 ppm surfactant). A comparison of both methods showed that partially substituted microbubble sparging increased oxygen uptake by 50%, final biomass levels by 17%, and final xanthan gum yield by 30%. Results indicate that X. campestris is amenable to conditions encountered within a microbubble generator and that microbubble sparging improved oxygen transfer and xanthan gum yield without affecting gum quality.     

新型氧弹量热仪测定谷物的热值

利用Parr公司所推出的新型6300氧弹量热仪首次对常见的几种谷物进行热值测定。准确称取一定量的待测物质,装入经高温灼烧干净的坩埚内,放入氧弹中充入高压纯氧,将测试样品在氧弹中完全燃烧,通过微处理器以及测量软件对整个测量过程进行控制,从而得到谷物的燃烧热值。本法原理准确,易操作,方法可靠,可为人们的膳食结构调整和日常检测提供科学依据。