耕牛轮牧对控制草洲感染性钉螺效果的研究

目的：探索耕牛轮牧对控制草洲感染性钉螺的效果。方法：选择翻阳湖中,重度疫区进贤县的军山湖乡为实验区,将该乡草洲划分为耕牛放牧区和禁牧区,每隔1两区轮换,耕牛进入放牧区前普治1次,同时,选择三里乡丰富行政村为对照区,耕牛敞放于草洲,每年普治1次,结果：实施安全轮牧的9块有螺草洲中,试前3块无感染螺,度后连续2年亦未发现感染螺,试前6块有感染螺的草洲,试后2年4块草洲感染性钉螺逐年下降到0,另外2块距村较近的]草洲仍有感染螺,感染螺放面下降了84．90％,耕牛感染率亦下降81．115,对照区6块草洲,试后2年感染螺面积下降20．83％,感染螺面积占有螺划洲面积的71．60％,耕牛感染率下降不显著,结论：草洲耕牛实施轮牧能有效地控制感染性钉螺密度,但离村较近草洲耕牛难以实施禁牧,感染螺密度得不到有效的控制。     

不同放牧强度对草地植被群落特征的影响

通过在塔城市北山铁列克提春秋牧场设置的轻度放牧(BA1)、中度放牧(BA2)、重度放牧(BA3)和对照四个水平放牧的测定,对不同放牧强度下草地植被的盖度、高度、密度以及生物量的变化进行了研究。结果表明:草地植被群落的主要优势种是草原苔草、千叶蓍、三叶草、早熟禾;不同放牧强度对植物群落具有一定的影响,其中草地植被群落盖度、密度和地上生物量随着放牧强度的增强均呈现下降趋势。     

洞庭湖区围栏封洲禁牧控制血吸虫病效果

目的观察洞庭湖区实施围栏封洲禁牧控制血吸虫病的效果。方法选择洞庭湖区沅江市冯家湾村为观察试点,调查围栏封洲禁牧前后人、畜、钉螺血吸虫感染率,家畜传染源数量和饲养方式,洲滩野粪分布,水体感染性,人畜在洲滩的活动情况,实施成本及其经济效益。结果围栏封洲禁牧2～5年后,人、畜、钉螺血吸虫感染率分别下降了88.89%、100%、100%,耕牛数量减少了73.60%,敞放饲养户减少了100%,舍饲圈养户增加了88.58%,人畜在洲滩的活动及污染减少,水体安全性增强,滩地生态经济效益提高了15%～20%。结论围栏封洲禁牧对控制湖区血吸虫病疫情具有积极作用。     

Influence of Tacticity on the Structure Formation of Poly(methacrylic acid) in Langmuir/Langmuir–Blodgett and Thin Films

A perfect isotactic poly(methacrylic acid) (it-PMAA) is synthesized and characterized by NMR spectroscopy. Surface pressure versus mean area per repeat unit (π−A) isotherms are recorded and compared with atactic poly(methacrylic acid) (at-PMAA). it-PMAA exhibits a π−A isotherm, indicating the formation of a stable Langmuir film. The isotherm has a characteristic pseudo-plateau at π of ≈11–14 mN  m⁻¹ attributed to the creation of worm-like entities confirmed by atomic force microscopy (AFM) in Langmuir–Blodgett (LB) films. These structures transform into spherical nanoparticles of ≈40 to 80 nm seen in LB films transferred at the end of the pseudo-plateau of the isotherm. Grazing incidence wide-angle X-ray scattering (GI-WAXS) shows a broad scattering signal (halo-like) at a q position of ≈11.12 nm⁻¹, revealing the amorphous nature of the nanoparticles. An ordered morphology, however, is observed in thin films prepared by precipitating it-PMAA from dimethylformamide (DMF) solution under vigorous stirring and coating them on a solid support. Optical microscopy (OM), AFM, and GI-WAXS reveal more details about the structure. Finally, various structural modifications of PMAAs are explained based on their tacticity and the subsequent hydrogen bonding effects between the carboxylic acid groups.