DETERMINATION OF STATIC AND DYNAMIC DIFFUSION COEFFICIENTS OF MOISTURE IN PARTICLEBOARDS

The static and dynamic diffusion coefficients are important coefficients todescribe the moisture transfer processes in particleboard.In this paper,the formula ofculculating the static and dynamic diffusion coefficients were deduced.At first,the staticdiffusion coefficients of four kinds of particleboards were determined by using diffusion cupmethod.The results demonstrated that the static diffusion coefficients parallel to panelsurface were 10-20 times as large as that of perpendicular to panel surface for test boards.To determine both dynamic diffusion coefficients and surface emission coefficients ofmoisture in particleboards in one experimental period,specimens in four different thickness-es of each kind of particleboard were used in the experiment.Then the method ofregression was used and the dynamic diffusion coefficients and surface emission coefficien-ts were determined based on the slope and intercept of the regressive line.     

Dynamic excitation and static loading tests of glulam lattice floor

A wooden lattice floor with high stiffness and damping capacity has been developed to solve noise problems in wooden apartment houses. The lattice floor consisted of Douglas fir glulam beams with inserted steel plate joints and drift pins. To examine the structural performance of the floor, dynamic excitation and static loading tests were conducted on the full size floor. The first and second order resonance frequencies of the floor were 13.5Hz and 27.0Hz, respectively. These frequencies are similar to the peak frequency of a conventional wooden floor and the combined floor fabricated from glued laminated timber and iron. The maximum static load of the floor was 127kN. The apparent flexural rigidity was less than half the value of several floors studied in the past. However, it is considered that the stiffness is improved by constructing panels and this floor has almost equivalent performance. Relative deflection was not affected by the loading history.Part of this study was presented at the International Wood Engineering Conference, New Orleans, October 1996.     

Safety of the tram car for slopes examined by stress analysis of the ground structure

For monorail systems, it is very important to ensure the safety of the ground structure. We developed a tram car for slopes that utilizes the mechanism of the monorail and analyzed the stress of the ground structure that had double rails. First, we divided the ground structure into seven components, and formulated a procedure for calculating the stress of the ground structure. As a result, the stress that acts upon the main rail and the main rail connecting part was near the allowable stress, and each calculated value was within the allowable stress. We measured the stress by running the vehicle, and compared the measured values with the calculated values. As a result, some measured values were larger than the calculated values. However, the ratio of measured value to allowable stress was 90% or less. Finally, we calculated the static loading coefficient for each part, results of which were as follows: main and subrail: 1.1; rail connection part and prop foundation part: 1.0; rail installation part: 1.3. In the recalculations, it became clear that the recalculated values exceeded the allowable stresses. These results suggest that we need to review the ground structure materials.     

基于UPLC-MS/MS同时测定猪粪便中5种兽药残留量的研究

为了建立同时测定猪粪便中二甲氧苄啶、磺胺对甲氧嘧啶、恩诺沙星、金霉素、泰乐菌素5种兽药残留量的超高效液相色谱-串联质谱(UPLC-MS/MS)分析方法,样品经McIllvaineNa_2EDTA缓冲溶液提取,C18粉吸附杂质,HLB固相萃取小柱净化,浓缩富集后用0.1%甲酸甲醇溶液复溶,过滤上机,基质液外标法定量。结果显示,5种兽药在10~500μg/kg的质量浓度范围内线性良好,在添加浓度50~500μg/kg,平均回收率为53%~85%,RSD为1.87%~18.81%。该方法具有较好的准确度与精密度,能快速、准确测定猪粪便中5种兽药残留,为养殖环节实时监测兽药使用情况提供了技术支持。     

Urinary and Plasma Catecholamines and Metanephrines in Dogs with Pheochromocytoma,Hypercortisolism, Nonadrenal Disease and in Healthy Dogs

Background

Diagnosis of pheochromocytoma (PC) is based on a combination of clinical suspicion, finding an adrenal mass, increased plasma, and urine concentrations of catecholamine metabolites and is finally confirmed with histopathology. In human medicine, it is controversial whether biochemically testing plasma is superior to testing urine.

Objectives

To measure urinary and plasma catecholamines and metanephrines in healthy dogs, dogs with PC, hypercortisolism (HC), and nonadrenal diseases (NAD) and to determine the test with the best diagnostic performance for dogs with PC.

Animals

Seven PC dogs, 10 dogs with HC, 14 dogs with NAD, 10 healthy dogs.

Methods

Prospective diagnostic clinical study. Urine and heparin plasma samples were collected and stored at −80°C before analysis using high‐pressure liquid chromatography (HPLC) coupled to electrochemical detection or tandem mass spectrometry were performed. Urinary variables were expressed as ratios to urinary creatinine concentration.

Results

Dogs with PC had significantly higher urinary normetanephrine and metanephrine : creatinine ratios and significantly higher plasma‐total and free normetanephrine and plasma‐free metanephrine concentrations compared to the 3 other groups. There were no overlapping results of urinary normetanephrine concentrations between PC and all other groups, and only one PC dog with a plasma normetanephrine concentration in the range of the dogs with HC and NAD disease. Performances of total and free plasma variables were similar. Overlap of epinephrine and norepinephrine results between the groups was large with both urine and plasma.

Conclusion and clinical importance

Measurement of normetanephrine is the preferred biochemical test for PC and urine was superior to plasma.     

双道原子荧光光谱同时测定土壤中砷、汞的方法研究

研究了土壤中总As、总Hg的同时测定方法,并对消化体系进行了筛选,利用正交试验设计法对测试条件进行了优化.建立了用王水消解样品,在10%盐酸溶液中用双道原子荧光光度计同时测定土壤中As、Hg的新方法.方法线性范围宽(As 0～200μg/L;Hg 0～10μg/L);检出限低(As 0.05μg/L;Hg 0.007μg/L);As的回收率为96.0%～101.0%,Hg的回收率为97.0%～103.7%;相对标准偏差(RSD)As为2.7%,Hg为4.5%.该方法准确、简便、快速,结果令人满意.     

无柄灵芝菌LZ02高产漆酶条件及部分酶学性质分析

【目的】 从采自新疆天山的无柄灵芝菌(G.resinaceum)中筛选获得1株高产漆酶的LZ02菌株,对其产酶条件进行优化,研究部分酶学性质。【方法】 采用单因素实验,对其产酶条件优化并研究其酶学特性,采用双向电泳检测酶蛋白。【结果】 LZ02菌株产漆酶的最佳碳源为2.5%麦麸+1%葡萄糖,最佳氮源为干酪素; Cu²⁺、Mg²⁺、Fe²⁺、 Zn²⁺和Ca²⁺的添加对LZ02产漆酶有一定的促进作用,而Co²⁺具有明显的抑制作用;藜芦醇和愈创木酚抑制产酶并使产酶高峰由第3 d推后至第9 d,添加没食子酸和ABTS对产酶影响不大,单宁酸对产酶有抑制作用。LZ02菌漆酶最适反应温度为60℃,且在80℃仍具有漆酶活性;在40℃,pH 4.0~5.0,酶活性最稳定;最适反应pH为3.0,Mn²⁺ 、Zn²⁺、 Cu²⁺ 、Ba²⁺和K⁺对酶稳定性有一定的促进作用,Co²⁺、Cd²⁺、Cr²⁺和Pb²⁺对酶的稳定性具有明显的破坏作用;对菌体及发酵液进行了双向电泳检测,测定其等电点为4.1;获得了1个纯化酶蛋白质谱序列,该蛋白与Ganoderma Lucidum来源的Laccase高度同源。【结论】 无柄灵芝菌(G.resinaceum)漆酶的合成和分泌受到营养水平、培养条件、生长阶段以及培养基中诱导剂的严格调控,木质素或木质素相关的芳香类化合物、N源和C源也能调节漆酶的合成;漆酶活性对不同种类、不同浓度的金属离子以及诱导剂的响应不尽相同,其具有较复杂的生理功能及调控机制。     

脂质分析技术及其在植物种子脂质 代谢调控研究中的应用进展

脂质是一类具有独特生理功能活性的化合物,参与调节多种植物应答非生物胁迫过程,对维持植 物组织中生理动态平衡至关重要。脂质组学（Lipidomics）自 2003 年被提出后,已迅速发展成为对脂质整体系 统分析的一门新兴学科,为传统代谢组学注入新的技术支撑,有助于阐明脂类物质在植物中的代谢调控机制。 同时,质谱成像技术因其具有无标记、非特异性、高灵敏度、多物质同时分析等优势,被广泛应用到植物组织 中各类脂质分子的空间分布研究。介绍了脂质组学和质谱成像技术的研究现状,重点综述脂质分析技术在植物 种子脂质代谢调控研究中的最新进展,特别是新兴质谱成像技术在植物种子中脂类物质的成像应用。脂质组学 和质谱成像技术作为目前多组学技术的重要补充,将为植物代谢途径和调控机制的深入探究提供新的契机。亚 微米级高空间分辨率质谱成像技术的不断发展,将进一步推动植物在空间分辨水平的脂质代谢调控网络的深入 解析和前沿应用研究。     

不同茶叶中游离氨基酸的对映异构体

【目的】游离氨基酸是茶叶的主要化学成分之一,与茶叶的滋味品质密切相关。大多数氨基酸具有手性中心,因此存在滋味特性及生理活性均可能截然不同的L型和D型两种对映异构体。由于检测技术的限制,过去的研究多集中在L型氨基酸上,而茶叶中D型氨基酸罕有系统的研究报道。因此,研究茶叶中游离氨基酸对映异构体,对茶叶化学理论体系的深化及滋味品质的提升与调控具有重要的推进作用。【方法】采用手性HPLC法、MTBSTFA硅烷衍生化法和酯化-PFP酰化法3种不同的分析方法对比茶叶中游离氨基酸对映异构体的分离性能,结果表明采用酯化-PFP酰化法结合手性气相色谱-质谱联用技术（gas chromatography-mass spectrometry,GC-MS）,可实现茶叶中丙氨酸、缬氨酸、苏氨酸、脯氨酸、亮氨酸、异亮氨酸、丝氨酸、半胱氨酸、天冬氨酸、蛋氨酸、苯丙氨酸、谷氨酸、酪氨酸、赖氨酸及色氨酸等15种重要游离氨基酸对映异构体的有效分离。继而建立茶叶中游离氨基酸对映异构体的高效衍生化及定性定量分析方法,并查明市售11种代表性白茶、乌龙茶及普洱茶中游离氨基酸对映异构体的分布规律。【结果】衍生化条件为：将氨基酸反应液在100℃下酯化105 min,继而以四氢呋喃为反应溶剂,在100℃下五氟丙酰化10 min。游离氨基酸对映异构体的回收率介于75.26%—123.6%（低浓度）、81.23%—121.8%（高浓度）,RSD值介于2.09%—13.12%（低浓度）、1.48%—10.59%（高浓度）。茶样分析结果表明,大部分氨基酸的1—2个对映异构体可以在茶样中检测出,且D-氨基酸普遍存在于茶样中,尤其是D-苏氨酸、D-天冬氨酸、D-半胱氨酸、D-苯丙氨酸、D-茶氨酸、D-谷氨酰胺及D-谷氨酸混合物在大部分茶样中均有分布,而D-蛋氨酸、D-赖氨酸及D-色氨酸在所有茶样中均未被检测出。在具体含量分布上,除了L-茶氨酸、L-谷氨酸及L-谷氨酰胺混合物之外,L-半胱氨酸（1.48—2.08 mg?g^-1）、D-半胱氨酸（1.46—1.49 mg?g^-1）、L-丝氨酸（0.15—1.80 mg?g^-1）及D-天冬氨酸（1.02—1.14 mg?g^-1）在白茶中的含量普遍较高;L-半胱氨酸（1.52—1.70 mg?g^-1）、D-半胱氨酸（1.45—1.49 mg?g^-1）、L-丝氨酸（1.03—1.50 mg?g^-1）、L-蛋氨酸（1.03—1.52 mg?g^-1）、L-酪氨酸（1.32—1.35 mg?g^-1）及D-天冬氨酸（1.01—1.15 mg?g^-1）在乌龙茶中具有较高含量。在普洱茶中,L-茶氨酸、L-谷氨酸及L-谷氨酰胺混合物的含量（1.04 mg?g^-1）与其他氨基酸相比并无显著性差异,而L-苏氨酸、L-色氨酸及L-丝氨酸含量较高,介于0.61—0.84 mg?g^-1。在氨基酸总量上,各茶类呈现出白茶（最高为40.61 mg?g^-1）>乌龙茶（最高为25.43 mg?g^-1）>普洱茶（8.01 mg?g^-1）的分布规律。多元统计分析结果表明,L-茶氨酸、L-谷氨酸及L-谷氨酰胺混合物、L-色氨酸及L-天冬氨酸在部分白茶中的含量显著高于乌龙茶,而L-酪氨酸与L-蛋氨酸则在乌龙茶中含量较高。【结论】D-氨基酸存在于大部分茶叶中,对茶汤滋味品质存在潜在影响,但在本研究样例中,D-氨基酸的含量分布在不同茶类间未表现出显著性差异。     

液液萃取-QuEChERS净化-高效液相色谱-串联质谱法测定饲料添加剂可溶性粉中五氯酚酸钠含量

建立液液萃取-QuEChERS净化-高效液相色谱-串联质谱法测定可溶性粉中五氯酚酸钠含量的新方法。 可溶性粉先用水溶解后加入1moL/L 盐酸1mL调pH至4左右,加入乙醚液液萃取到乙醚层,蒸干乙醚,乙腈复溶,QuEChERS净化管净化后高效液相色谱-串联质谱测定,标准曲线外标法定量。 五氯酚酸钠在0.50~100μg/L质量范围内线性关系良好,相关系数为0.9994,检出限0.5μg/kg,定量限1.0μg/kg,可溶性粉剂中五氯酚酸钠添加量为1.0、5.0、10.0μg/kg时,五氯酚酸钠的平均回收率为80.2%~94.0%,相对标准偏差小于7%。 该方法快速、高效且价格低廉,适用于饲料添加剂可溶性粉中五氯酚酸钠的快速筛查分析测定。