厚膜ZrO_2氧敏元件的制作工艺对其氧敏特性的影响

报道了不同的制作工艺对厚膜ＺｒＯ＿２氧敏元件的氧敏特性的影响。实验结果表明，采用工艺Ｂ能够提高元件灵敏度。     

常温振荡式CO气敏元件的研制

常温振荡式ＣＯ气敏元件的研制孙良彦，刘正绣（吉林大学电子工程系长春１３００２３）关键词常温元件；振荡；一氧化碳；气敏元件中图分类号ＴＰ２１２．２目前已实用化的半导体气敏元件大多是加热式的，随着科学技术的发展，工业及日常生活等领域对可燃气体及毒性气体（...     

常温乙炔敏感振荡元件研究

报道了一种新型乙炔气体敏感元件。这种元件以Ｓｎｏ２为基体材料，工作在室温条件，对低浓度Ｃ２Ｈ２气体非常敏惑，对１０００ｐｐｍＨ２几乎没有气敏响应；其输出特性与一般加热元件明显不同，呈现为规律性极强的振荡波形，并对这种元件的气敏振荡机理进行了讨论．     

用于环境监测的气敏元件开发研究

以纳米级 Sn O2 为气敏材料制作了气敏元件 ,以无机试剂为前驱原料加入少量适当的溶胶形成助剂 ,采用溶胶 -凝胶法制备了纳米级 Sn O2 .通过研究不同掺杂量和不同加热条件下这类气敏元件对几种还原性气体的灵敏度和选择性 ,为开发用于环境监测的新型高灵敏度和高选择性的气敏元件提供技术数据 .     

添加剂对氧化钛气敏材料敏感特性的影响

采用化学共沉淀法和浸渍法制备了不同金属或氧化物掺杂的ＴｉＯ２气敏材料，通过透射电镜、电子衍射和ｘ射线衍射对材料的结晶形态和物相进行了分析，用静态配气法测试了气敏材料的敏感特性．结果表明：这些材料的颗粒尺寸小于０．１μｍ，８００℃处理样品为金红石型ＴｉＯ２与锐钛矿型ＴｉＯ２的混合物．通过选择合适的添加剂和工作温度可分别获得选择性酒敏元件、ＣＯ气敏元件和可燃气体普敏元件     

导电微纳纤维复合纱的制备及其气敏特性

为开发高质量的气敏传感器,利用水浴静电纺丝法制备以涤纶(PET)为芯纱,聚酰胺6(PA6)纳米纤维为包覆层的微纳纤维复合纱(MNY),基于原位聚合方法对MNY进行连续导电处理,制备微纳米纤维复合纱/聚苯胺(MNY/PANI)复合导电纱,以此作为气敏元件,同时将相同参数下制备的PET/PANI复合导电纱也作为气敏元件进行对照,探究不同结构纱线之间气敏效果的差异。研究结果表明：MNY具备良好的皮芯结构,经导电处理后MNY表面均匀分布了聚苯胺颗粒,MNY/PANI的电导率最高可达7.53 S/cm;相比于PET/PANI气敏元件,MNY/PANI气敏元件因其纳米结构的高比表面积对NH₃的灵敏度更高,能表现出更好的响应-恢复效果,重复性和稳定性更好,已初步具备了作为优良气敏元件的条件。     

Au-SnO2高温CO气敏元件的研制

在 Ｓｎ Ｏ２ 基体材料中掺杂 Ｔｈ Ｏ２ 及 Ａｕ, Ｐｄ 等贵金属催化剂,获得了２７０ ℃高温区域对 Ｃ Ｏ 具有高灵敏度的气敏元件．通过活性碳过滤技术,改善了该元件的选择性．测试结果表明,该元件具有良好的稳定性,是一种实用化的 Ｃ Ｏ气敏元件．     

SnO_2气敏元件热特性规律的研究

ＳｎＯ＿２气敏元件热特性规律的研究迟宗涛，孙林学（青岛大学物理系青岛２６６０７１）关键词元件阻值；加热电流；材料常数；工作系数中图分类号ＴＰ２１２．２通过测试国内某厂家生产的ＳｎＯ２系烧结型旁热式气敏元件阻值Ｒ随加热电流ＩＢ变化的规律，给出空气中元件...     

SnO_2－SiO_2双层薄膜氢敏元件的特性研究

采用溶液－凝胶浸渍涂布工艺在Ａｌ＿２Ｏ＿３陶瓷管上制备了掺杂ＳｎＯ＿２气敏薄膜；利用高温热解法在ＳｎＯ＿２薄膜表面覆盖ＳｉＯ＿２气体分离膜后制得双层薄膜气敏元件。分别测试并比较单层和双层薄膜元件的气敏特性，结果表明：单层薄膜元件对可燃性气体无选择性、响应和恢复时间短；而双层薄膜元件对氢气表现出极高的灵敏度和优越的选择性，其响应和恢复时间都比单层薄膜元件有所延长，结合实验结果，从理论上阐述了双层薄膜元件对氢气的敏感机理。     

厚膜湿敏浆料及其元件的研制

叙述了厚膜湿敏浆料及其元件的研制过程。厚膜湿敏浆料是以硅凝胶、碳黑、石墨、玻璃粉等分散在有机溶剂中制得的，具有均匀、稳定可靠的优点，由此种浆料制成的厚膜湿敏元件测量范围宽，温度系数小，响应快，一致性好，工艺简单，宜于批量生产     

Oxygen-Sensor-Based Simple Assay of Histamine in Fish Using Purified Amine Oxidase

Oxygen consumption was measured by an oxygen sensor after addition of purified fungal amine oxidase to fish extracts. The oxidation of histamine to imidazoleacetaldehyde proceeded stoichiometrically. Based on the equimolar relationship between histamine and oxygen consumption, histamine was determined selectively by the oxygen sensor. Neither sample pretreatment removing interfering materials nor daily calibration by histamine standard was required. Histamine contents in scombroid fish were determined rapidly with good accuracy. AOAC and oxygen sensor methods showed a very high correlation (r=0.999, n=6).     

固体超强酸S_2O_8~(2-)/ZrO_2-CeO_2催化制备聚乙二醇菜籽油脂肪酸酯的研究

以固体超强酸S2O82-/ZrO2-CeO2为催化剂,将菜籽油醇解所得脂肪酸甲酯与聚乙二醇400(PEG-400)酯交换制备非离子表面活性剂聚乙二醇菜籽油脂肪酸酯。考察了反应物质量比、催化剂用量、反应时间、反应温度和催化剂重复使用等因素对反应的影响。结果表明,在m(脂肪酸甲酯)∶m(PEG-400)=2.8∶1,催化剂用量为反应物总质量的1.5%,温度为130℃,反应7 h时,PEG-400的酯交换率为91.56%,催化剂重复使用5次后,PEG-400的酯交换率仍比较高。用傅里叶红外光谱仪、表面张力仪等手段对产品的结构和理化性能进行了考察,产品的浊点指数为19.98 mL、表面张力γ(临界胶束浓度)为27.04 mN/m、乳化力622 s、润湿力59 s,具有很好的表面活性。     

Selective determination of lactic acid in dry-fermented sausages using a sensor based on immobilized lactate oxidase

Selective determination of lactic acid in dry-fermented sausages is an indicator of quality and its presence prevents the growth of pathogenic bacteria. The analysis of lactic acid represents a high cost for the relevant food industries. The use of an enzymatic sensor would allow to reduce the time and cost of this analysis. An enzymatic sensor employing lactate oxidase (LacOx) with the immobilized enzyme system in combination with an oxygen electrode was optimized to determine the lactic acid content in dry-fermented sausages. In this study using LacOx from Pediococcus sp., a voltage of ?600 mV, low volumes of reaction and the amperometric signal obtained due to the oxygen depletion (consumed oxygen) during the lactic acid oxidation was recorded at 15 s in the immobilized enzyme sensor so that the reaction rates (slope) were related to the lactic acid content. A positive linear relationship between the consumed oxygen as a function of time (mg O2/L*s^?1) and the lactic acid concentration in the range of 250–600 μM, with a coefficient ofR² = 0.9936 for the immobilized enzyme system, was determined. The immobilized enzyme sensor showed a high specificity K_M = 0.865 and sensitivity of 0.25 mM and was stable enough to allow the reutilization of the membranes up to 20 times without loss of activity, where 90% of its initial activity remained after 45 days. The analysis of lactic acid with the immobilized enzyme system in dry-fermented sausages revealed very good agreement with the determination performed through standard HPLC methodology using the same linear range in both methods, which validated the use of this sensor as an alternative technique to evaluate cured meat quality.     

Selective Determination of Lysine in Dry-Cured Meats Using a Sensor Based on Lysine-α-Oxidase Immobilised on a Nylon Membrane

An enzymatic sensor employing lysine oxidase (LOx) with the immobilised enzyme system by crosslinking with glutaraldehyde using an immunodyne ABC nylon membrane, in combination with an oxygen electrode, has been optimised to determine the lysine content in dry-cured ham and dry-fermented sausage at different cured times. The amperometric signal obtained due to the oxygen depletion (consumed oxygen) during the lysine oxidation was recorded at 5 s in the immobilised enzyme sensor, and the reaction rates (slope) were related to the lysine content. A linear relationship between the consumed oxygen as a function of time (mg O₂/l/s) and the lysine concentration in the range 10–250 μM (R ²?=?0.9946) for the immobilised enzyme system was found. The immobilised enzyme sensor showed a high specificity and sensibility. Nevertheless, the stability of the immobilised enzyme at the assay temperature was very poor, and thus, a new membrane was required for each analysis. The analysis of lysine with the immobilised enzyme system in cured meat samples revealed very good agreement with the determination performed through standard HPLC methodology, which validated the use of this sensor as an alternative technique to evaluate cured meat quality.     

伽伐尼电池式氧传感器敏感机制及性能提高

对伽伐尼电池式氧传感器的敏感机制进行了探讨，详细论述了影响电池敏感特性的因素并给出了提高传感器灵敏度、缩短响应时间和延长使用寿命的方法，文中有关钝化的理论与相关参考文献不同，采用了一些特殊手段来制作高性能的传感器。     

Peroxisomal metabolism is regulated by an oxygen-recognition system through organelle crosstalk between the mitochondria and peroxisomes

In the present study using Pichia methanolica, it was found that expressions of methanol-metabolic enzymes were strictly regulated by the presence of oxygen, and that induction of alcohol oxidase (AOD) isozymes was completely dependent on oxygen concentrations. A proportion of AOD-isozyme species responded to oxygen conditions, e.g. in a low oxygen condition, Mod1p was dominant, but with an increase in the oxygen concentration, the ratio of Mod2p increased. The K(m) value of Mod1p for oxygen was ca. one-seventh lower than that of Mod2p (0.47 and 3.51 mM, respectively). This shows that Mod1p is suitable at low oxygen concentrations and Mod2p at high oxygen concentrations. Also, zymogram changes for AOD isozymes were observed by inhibition of respiratory chain activity. These indicated that P. methanolica has the ability to recognize oxygen conditions and the respiratory chain should participate in the sensor for available oxygen. These facts indicate that there is organelle crosstalk between mitochondria and peroxisomes through nucleus gene regulation in order to control the consumption balance of available oxygen between the mitochondrial respiratory chain and peroxisomal AODs.     

透过率检测技术在食品包装材料阻隔性分析中的应用

食品包装对食品安全有很大影响,包装材料的氧气和水蒸气阻隔性是保护食品品质的重要因素。本文对国家标准及相关文献进行综述,详细阐述了食品包装材料的氧气及水蒸气阻隔性的各种检测方法原理,并对其进行比较,总结方法的适用性。氧气透过率检测有压差法和库仑计法2种方法,压差法的成本和精准度相对较低,库仑计法的成本和精准度均相对较高;水蒸气透过率的检测有红外检测器法和电解传感器法,其中红外检测器法优于电解传感器法。最后对透过率检测在食品包装材料领域的应用进行了介绍,同时对今后阻隔性研究的发展方向进行了展望。     

不同包装条件下冷却肉品质变化及腐败菌相研究

为寻找冷却猪肉合理的包装方式,延长货架期,将猪后腿肉分别进行托盘包装、真空包装、高氧气调包装（20%CO₂+80%O₂）和低氧气调包装（65%CO₂+35%O₂）处理,并以无包装组为对照,测定样品在4℃贮藏过程中挥发性盐基氮（TVB-N）值、色差值a*、丙二醛（MDA）值、微生物菌落（菌落总数、假单胞菌菌落数和热杀索丝菌菌落数）和感官评分。结果表明:无包装和托盘包装冷却猪肉货架期不超过4 d,高氧气调包装（20%CO₂+80%O₂）货架期为6 d,真空包装和低氧气调包装（65%CO₂+35%O₂）货架期长达9 d。真空和气调包装均有利于延长冷藏猪肉货架期,但真空包装使肉呈暗红色。气调包装中O₂和CO₂的含量影响肉的品质,高氧气调包装有利于好氧菌假单胞菌和热杀索丝菌的生长繁殖,同时促进脂质氧化,但可以很好维持肉色,低氧气调包装（65%CO₂+35%O₂）可以抑制细菌的生长和脂肪氧化。综合各项评判结果,得到最佳包装方式为低氧包装（65%CO₂+35%O₂）。      

Hypoxanthine-based enzymatic sensor for determination of pork meat freshness

An enzyme sensor employing xanthine oxidase (XO), soluble or immobilised, in combination of an oxygen electrode has been developed and optimised to determinate the hypoxanthine (Hx) content in pork meat at different post-mortem times as measure of meat freshness. The amperometric signal obtained due to the oxygen depletion during the Hx oxidation was related with the consumed oxygen at 190 s in the soluble enzyme sensor or enzymatic rate at 10 s in the immobilised enzyme sensor. In both cases a linear relationship between the signal and the Hx concentration in the range 8.68–26.05 μM (R² = 0.999) and 15.63–127 μM. (R² = 0.995), respectively, was found. Both enzyme sensors exhibited very good working conditions and storage stability. A study of Hx oxidation was carried out in order to compare the Hx content measured by both sensors and those measured by high performance liquid chromatography (HPLC) obtaining a good agreement between both techniques. Therefore, the easy preparation and operation of both enzyme sensors suggests a reliable, rapid and an economical alternative for simple or multiple Hx measurements constituting a useful tool as quality control of meat freshness.