电化学法快速测定茶多酚含量的研究

基于电化学循环伏安法,讨论了3种低成本自制工作电极——银电极、碳糊电极和玻碳电极在茶多酚含量测定应用上的可行性。通过分析茶多酚在电极表面的氧化还原行为,发现所制银电极不适宜检测茶多酚,碳糊电极、玻碳电极的氧化电流峰值与茶多酚含量有良好的线性关系。所制玻碳电极测定绿茶茶样中的茶多酚含量的重复性和准确性较碳糊电极好。与国标方法相比,碳糊电极、玻碳电极检测茶多酚所需时间大大缩短。结果表明,电化学方法可应用于茶多酚含量的快速测定,从而为快速、低价、便捷检测茶多酚提供一条新思路。     

Total soil heavy‐metal concentrations and mobile fractions after 10 years of biowaste‐compost fertilization

The accumulation of heavy metals (HMs) in soils is the most often cited potential risk of compost application. As the ecological effects of metals are related to mobile fractions rather than to total concentrations in the soil, we measured the total (aqua regia–extractable) HM concentrations, the readily available water‐soluble and the potentially bioavailable LiCl‐extractable fraction of soil HMs in a field experiment after 10 y with total applications of 95, 175, and 255 t ha^–1 biowaste compost (fresh matter). Total soil concentrations of Cd, Cr, Cu, Ni, and Pb in the compost treatments were not significantly higher than in the unfertilized control. Total Zn concentrations increased in the treatment with the highest application rate, as expected from the calculation of the Zn load in the composts. In the mobile fractions, as measured in soil saturation extract and LiCl extract, Cd and Pb were not detectable. Concentrations of Cr, Ni, and Zn were in the range published for unpolluted soils in other studies and did not show any differences according to treatment. Easily exchangeable Cu (in LiCl extract) was increased with compost fertilization, most probably due to complexation with low‐molecular organic complexants. Except for Cd and Zn, the results of the mobile HM fractions in the soil were in good agreement with plant HM concentrations. In conclusion, fertilization with high‐quality biowaste compost at such rates and after 10 y of application gives no cause for concern with regard to both total HM concentrations and available HM fractions.     

影响钢模板及循环钢模带使用寿命的各种因素

花纹钢模板及循环钢模带目前正广泛地应用于层压板的生产工艺,其品质的优劣好坏会直接影响到最终产品的质量。笔者结合所在公司——山特维克传动     

Long‐term application of biowaste compost versus mineral fertilization: Effects on the nutrient and heavy metal contents of soil and plants

In recent years the use of biowaste compost (BC) as a soil amendment is of increasing interest. The aim of the experiment was to investigate the influence of different fertilization systems: biowaste compost, annual average of 32 Mg ha^—1 BC (fresh matter) and mineral fertilizer (83:52:95 kg ha^—1 NPK fertilizer) on the nutrient and heavy metal contents of soil and plants. Soil samples (1997) and harvest products (1996—1998) from a field trial (initiated 1992) were analyzed for K, Mg, P, Cu, Mn, Mo, Zn, Cd, Ni, and Pb. The five‐year fertilization with composted biowaste did not influence the total contents of Cd, Mn, Mo, and Ni in soil. The total soil contents of Zn and Pb were significantly higher in soils of the BC treatment than in the unfertilized control. Both fertilized plots tended to have higher Cu and Zn contents in harvest products than the unfertilized control. The mineral fertilization inhibited the Mo uptake by plants. In 1998 the mineral fertilization led to higher, and the biowaste compost application to lower, Cd contents in potato tubers as compared to the control.     

Chemistry,stereochemistry and biological properties of KWG 4168

KWG 4168 (8-tert-butyl-1,4-dioxaspiro[4,5]decan-2-ylmethyl(ethyl)(propyl)amine; proposed common name spiroxamine) is a new fungicide consisting of four biologically active isomers (two diastereomers, four enantiomers). The four isomers were separated by preparative HPLC on a chiral stationary phase. The diastereoisomers were synthesised from the corresponding chirally pure glycerol derivatives and were separated by preparative HPLC. COSY, HSQC and NOESY NMR spectroscopy were used to asign the configuration of the amino residue relative to the cyclohexyl ring. Studies of the activity against wheat powdery mildew, as well as the inhibition of sterol biosynthesis in fungi by the four stereoisomers, indicate the contribution of each isomer to the biological activity of spiroxamine.     

CT AND MRI FEATURES OF CAROTID BODY PARAGANGLIOMAS IN 16 DOGS

Carotid body tumors (paragangliomas) arise from chemoreceptors located at the carotid bifurcation. In imaging studies, this neoplasm may be confused with other neck neoplasms such as thyroid carcinoma. The purpose of this retrospective, cross‐sectional study was to describe computed tomographic (CT) and magnetic resonance imaging (MRI) characteristics of confirmed carotid body tumors in a multi‐institutional sample of dogs. A total of 16 dogs met inclusion criteria (14 examined using CT and two with MRI). The most common reason for imaging was a palpable cervical mass or respiratory signs (i.e., dyspnea or increased respiratory noises). The most commonly affected breed was Boston terrier (n = 5). Dogs were predominantly male castrated (n = 10) and the median age was 9 years [range 3–14.5]. Most tumors appeared as a large mass centered at the carotid bifurcation, with poor margination in six dogs and discrete margins in ten dogs. Masses were iso‐ to hypoattenuating to adjacent muscles in CT images and hyperintense to muscles in T1‐ and T2‐weighted MRI. For both CT and MRI, masses typically showed strong and heterogeneous contrast enhancement. There was invasion into the adjacent structures in 9/16 dogs. In six of these nine dogs, the basilar portion of the skull was affected. The external carotid artery was entrapped in seven dogs. There was invasion into the internal jugular vein in three dogs, and into the external jugular, maxillary, and linguo‐facial veins in one dog. Imaging characteristics helped explain some clinical presentations such as breathing difficulties, Horner's syndrome, head tilt, or facial nerve paralysis.     

PREVALENCE,ASSOCIATION WITH STIFLE CONDITIONS,AND HISTOPATHOLOGIC CHARACTERISTICS OF TIBIAL TUBEROSITY RADIOLUCENCIES IN DOGS

A tibial tuberosity radiolucency is sometimes identified on lateral radiographs of canine stifle joints, however little is known about the cause or significance. The purpose of this study was to describe the prevalence, association with other stifle conditions, and histopathologic characteristics of tibial tuberosity radiolucencies in a group of dogs. Radiographs of all canine stifle joints over 5 years were evaluated. Presence or absence of a tibial tuberosity radiolucency was recorded by an observer who was unaware of clinical status. Patient signalment and presence of other stifle joint conditions were recorded from medical records. A tibial tuberosity radiolucency was found in 145/675 dogs (prevalence = 21.5%). Statistically significant associations were identified between tibial tuberosity radiolucency and stifle condition (P < 0.0001), breed size (P = 0.011), and younger age of presentation (P = 0.001), but not with gender (P = 0.513). Dogs with a tibial tuberosity radiolucency had higher odds of having a medial patellar luxation than dogs without (OR = 9.854, P < 0.0001, 95% CI 6.422–15.120). Dogs with a tibial tuberosity radiolucency had lower odds of having a cranial cruciate ligament rupture than dogs without (OR = 0.418, P < 0.0001, 95% CI 0.287–0.609). Four canine cadavers, two with normal stifles and two with tibial tuberosity radiolucencies, underwent radiographic, computed tomographic, and histologic examination of the stifles. Computed tomography revealed a hypoattenuating cortical defect in the lateral aspect of the proximal tibial tuberosity that corresponded histopathologically to a hyaline cartilage core. Findings indicated that the tibial tuberosity radiolucency may be due to a retained cartilage core and associated with medial patellar luxation in dogs.     

IMAGING DIAGNOSIS—ULTRASONOGRAPHIC AND CT FINDINGS IN A GRAY SEAL (HALICHOERUS GRYPUS) WITH HEPATIC CIRRHOSIS,PYELONEPHRITIS, AND NEPHROLITHIASIS

An immature gray seal was presented with lethargy, weight loss, vomiting and hematuria. Hepatic disease and urinary tract infection were suspected. Abdominal ultrasound showed hyperechoic structures with marked acoustic shadowing spread throughout both kidneys, but incomplete visualization of the liver. Abdominal CT showed mineral densities scattered throughout both kidneys and poor delineation of the liver. Due to the poor quality of life, the seal was euthanized. Postmortem examination showed ammonium urate nephroliths, pyelonephritis, and hepatic cirrhosis. This case report emphasizes the difficulty of characterizing liver disease with conventional 2D‐ultrasound and CT in a deep‐chested animal with minimal intra‐abdominal fat.