液相色谱-串联质谱法测定鸡组织中沃尼妙林残留

建立了鸡组织中沃尼妙林残留的液相色谱-电喷雾串联质谱(LC-ESI-MS /MS) 检测方法.样品用乙腈提取后,过Strata-X-C固相萃取小柱净化.以乙腈-0.1%甲酸水溶液(35∶ 65,V/V)为流动相,经Luna C18色谱柱分离,采用电喷雾电离,多反应监测(MRM)正离子模式对沃尼妙林进行定性与定量分析.采用基质匹配法,对鸡皮肤、肌肉、肾脏和肝脏中沃尼妙林的含量进行标准校正,在5(7.5)～500 μg/kg范围内线性良好(r>0 998),在鸡肝脏中的检出限(LOD)及定量限(LOQ)分别为4.0和7.5 μg/kg;其它3种组织中的LOD及LOQ分别为2.5和5.0 μg/kg.在5(7.5), 50及500 μg/kg添加水平下,4中组织中沃尼妙林的平均回收率为78 5%～104.0%.日内相对标准偏差(RSD)为1.2%～9.8%,日间相对标准偏差为3.7%～13.2%.     

Smoothed particle hydrodynamics formulation for penetrating impacts on ballistic gelatine

A particle method is applied to the investigation of impact biomechanics in the case of penetrating ballistic. A three dimensional model is proposed using the Smoothed Particle Hydrodynamics (SPH) method combined with Finite Elements (FE) method. The problem consists in the violent impact of a steel sphere on soft tissues, simulated by 20% ballistic gelatine (BG) material which is considered as a very interesting human tissue surrogate. Comparisons with experimental data are established to validate the proposed model. The results, in terms of penetrating curves, show very promising results. The use of particle methods appears to be an interesting way to model high speed loading, especially penetrating ballistic impact whose classical FE modelling can bring some important limitations in terms of mesh and element distortions.     

Ultrasound-enhanced diffusion through isolated frog skin

The effect of ultrasound on the transport of oxygen across excised frog abdominal skin has been studied. Samples were mounted in an exposure chamber in which the Ringer's solution on one side was saturated with oxygen while the other side of the skin had a low initial oxygen concentration. They were treated with ultrasound at 1, 1.5 and 2 W cm⁻² SATA c.w., respectively, and increases in the rate of oxygen transport were observed at all intensities. These increases ranged from 38 ± 4% at 1 W cm⁻² to 55 ± 8% at 2 W cm⁻². Variation in the pulse lengths from 25 to 200 ms and a constant average intensity did not affect the rate of transport significantly provided that the temporal intensity was constant. Since the peak acoustic pressure within the pulse increased with decreasing pulse length and increasing acoustic pressure increases the probability of cavitation occurring, the mechanism responsible for this phenomenon is probably not cavitation.     

用快速低温冷冻和ESK方法分析兔脂肪栓塞脑组织中自由基

用快速低温冷冻-ESR实验方法研究兔脂肪栓塞模型脑组织自由基的变化,实验发现脂肪栓塞实验组自由基相对浓度是正常对照组的2-3倍。ESR检测到脂类过氧化自由基和以碳为中心的烷基类自由基的事实表明脂肪栓塞病变存在活性氧自由基作用过程。文中对快速冷冻法可行性进行评估。     

Optimization of butyltin measurements for seawater,tissue, and marine sediment samples

Optimized techniques for measuring butyltins at the sub-part-per-trillion (ppb; 1:10¹²) level in seawater and at the part-per-billion (ppb; 1:10⁹) level in tissues and sediments are presented. Purge and trap/hydride derivatization followed by atomic absorption (AA) detection was optimized to give better sensitivity than was previously attained for seawater, yielding environmental detection limits of 0.08–0.2 ng dm^?3. Improvement in precision and reproducibility in measurement of butyltins in tissues and sediments was attained by adjustment of the concentration in an organic extract to minimize matrix effects and by use of internal standards. The tissues and sediments were homogenized and extracted with methylene chloride (CH₂Cl₂) after acidification. The butyltins in the organic layer were derivatized with hexylmagnesium bromide and analyzed by gas chromatography (GC) with a flame photometric detector (FPD). The absolute detection limits in tissues and sedimets were 0.1 ng for tributyltin (TBT), 0.12 ng for dibutyltin (DBT) and 0.29 ng for monobutyltin (MBT).     

生物组织非线性光学二次谐波及其层析成像分析

对生物组织中的二次谐波进行了理论分析，通过求解耦合波方程得到高散射介质中二次谐波的表达式，得出了具有高散射性的生物组织中的二次谐波理论模型，给出了散射因子的具体形式并作出了初步分析。并用蒙特卡罗方法分析了紧聚焦高斯光对生物组织进行二次谐波层析成像过程，得出了在探测生物组织不同深度时，探测点附近二次谐波的空间纵向分布及二次谐波信号光的强度变化。     

A new liquid chromatographic method for routine determination of oxytetracycline marker residue in the edible tissues of farm animals

A simple, rapid, and specific ion-pair liquid chromatographic method for routine determination of the marker residue of oxytetracycline (OTC), namely OTC and 4-epi-oxytetracycline (4-epiOTC), in edible animal tissues (muscle, liver, kidney, and fat) has been developed. Minced tissue samples were acidified at pH 2.7 with 2 mol L(-1) sulfuric acid and extracted with acetonitrile. The extracts were purified by treatment with ammonium sulfate solution and concentrated into 0.1 mol L(-1) phosphoric acid. Baseline separation was carried out isocratically on a Nucleosil 100-5 C(18), 5-microm column using an acetonitrile-0.01 mol L(-1) disodium hydrogen phosphate (20:80, v/v) mobile phase that contained both positively (tetrabutylammonium) and negatively (octanesulfonate) charged pairing ions and EDTA, and was adjusted to pH 3.8. Detection was by UV at 370 nm. The method was fully validated according to Commission Decision 2002/657/EC. Overall recoveries were better than 82.6% and overall relative standard deviation was better than 6% for all the tissues examined. The good analytical characteristics of the method allowed limits of quantification as low as 30 ng g(-1) for muscle and fat and 50 ng g(-1) for liver and kidney, for both OTC and 4-epiOTC, to be realized. The method was successfully used to determine the OTC marker residue in tissues of two sheep intramuscularly administered a commercial OTC formulation.     

Modeling of growth and remodeling in soft biological tissues with multiple constituents

Among the various important characteristics of biological tissues is their ability to grow and remodel. It is well-known that one of the primary triggers behind the growth and remodeling process is changes in the mechanical environment, for instance changes in stress, strain, etc. These mechanisms of mechanotransduction are the driving force behind many changes in structure and function including growth and remodeling. The purpose of this article is to formulate better constitutive equations for the stress in tissues with multiple constituents undergoing growth and remodeling. This is a very complex problem and is of tremendous importance. Here, we do the modeling from a mechanics point of view, utilizing the theory of natural configurations coupled with population dynamics to accurately model the production and removal of the different constituents that comprise the tissue. This is accomplished by deriving a generalized McKendrick equation for growth and remodeling and has the advantage of directly including the age distribution of constituents into the model. The population distribution function is then used to determine the stress in the tissue.     

鸡组织中3种青霉素类药物残留检测的前处理方法比较研究

采用高效毛细管电泳(HPCE)分离紫外检测方法,比较了乙腈萃取、乙腈萃取-固相萃取(SPE)、基质固相分散萃取(MSPD)和MSPD - SPE 4种方法对鸡组织样品中青霉素、氨苄青霉素、阿莫西林残留的前处理效果.结果表明,与其他方法相比,MSPD方法的回收率高、图谱背景干净.据此建立了鸡组织中青霉素、氨苄青霉素、阿莫...